Add barebones device trees for frankel (Pixel 10), blazer (Pixel 10
Pro), and mustang (Pixel 10 Pro XL). These device trees are enough to
boot to a serial prompt using an initramfs.
Many things can be noted about these device trees:
1. They are organized as "dts" files for the main SoC and "dtso"
overlays for the boards. There is discussion about this in the
bindings patch ("dt-bindings: arm: google: Add bindings for
frankel/blazer/mustang").
2. They won't boot with the currently shipping bootloader. The current
bootloader hardcodes several paths to nodes that it wants to update
and considers it a fatal error if it can't find these nodes.
Interested parties will need to wait for fixes to land and a new
bootloader to be rolled out before attempting to use these.
3. They only add one revision (MP1) of each of frankel, blazer, and
mustang. With this simple barebones device tree, there doesn't
appear to be any difference between the revisions. More revisions
will be added as needed in the future. The heuristics in the
bootloader will pick the MP1 device tree if there are not any
better matches.
4. They only add the dts for the B0 SoC for now. The A0 SoC support
can be added later if we find the need.
5. Even newer versions of the bootloader will still error out if they
don't find a UFS node to add calibration data to. Until UFS is
supported, we provide a bogus UFS node for the bootloader. While
the bootloader could be changed, there is no long-term benefit
since eventually the device tree will have a UFS node.
6. They purposely choose to use the full 64-bit address and size cells
for the root node and the `soc@0` node. Although I haven't tested
the need for this, I presume the arguments made in commit
bede7d2dc8f3 ("arm64: dts: qcom: sdm845: Increase address and size
cells for soc") would apply here.
7. Though it looks as if the UART is never enabled, the bootloader
knows to enable the UART when the console is turned on. Baud rate
is configurable in the bootloader so is never hardcoded in the
device tree.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
To avoid fragmenting the discussion, IMO:
* Let's have the discussion about using the "dts" for SoC and the
"dtso" for the boards in response to the bindings (patch #1).
* If we want to have a discussion about putting "board-id" and
"model-id" at the root of the board overlays, we can have it
here. I'll preemptively note that the "board-id" and "model-id"
won't show up in the final combined device tree and they are just
used by the tool (mkdtimg). We could change mkdtimg to parse the
"compatible" strings of the overlays files (since I've put the IDs
there too), but official the docs [1] seem to indicate that
top-level properties like this are OK.
In order for these device trees to pass validation without warnings,
it's assumed you have my dtc patches:
* https://lore.kernel.org/r/20251110204529.2838248-1-dianders@chromium.org
* https://lore.kernel.org/r/20251110204529.2838248-2-dianders@chromium.org
[1] https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-object-internal.txt?h=main
arch/arm64/boot/dts/google/Makefile | 9 +
arch/arm64/boot/dts/google/lga-b0.dts | 391 ++++++++++++++++++
.../arm64/boot/dts/google/lga-blazer-mp1.dtso | 22 +
.../boot/dts/google/lga-frankel-mp1.dtso | 22 +
.../boot/dts/google/lga-mustang-mp1.dtso | 22 +
.../boot/dts/google/lga-muzel-common.dtsi | 17 +
6 files changed, 483 insertions(+)
create mode 100644 arch/arm64/boot/dts/google/lga-b0.dts
create mode 100644 arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
create mode 100644 arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
create mode 100644 arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
create mode 100644 arch/arm64/boot/dts/google/lga-muzel-common.dtsi
diff --git a/arch/arm64/boot/dts/google/Makefile b/arch/arm64/boot/dts/google/Makefile
index a6b187e2d631..276001e91632 100644
--- a/arch/arm64/boot/dts/google/Makefile
+++ b/arch/arm64/boot/dts/google/Makefile
@@ -1 +1,10 @@
# SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+
+dtb-$(CONFIG_ARCH_GOOGLE) += \
+ lga-blazer-mp1.dtb \
+ lga-frankel-mp1.dtb \
+ lga-mustang-mp1.dtb
+
+lga-blazer-mp1-dtbs := lga-b0.dtb lga-blazer-mp1.dtbo
+lga-frankel-mp1-dtbs := lga-b0.dtb lga-frankel-mp1.dtbo
+lga-mustang-mp1-dtbs := lga-b0.dtb lga-mustang-mp1.dtbo
diff --git a/arch/arm64/boot/dts/google/lga-b0.dts b/arch/arm64/boot/dts/google/lga-b0.dts
new file mode 100644
index 000000000000..83c2db4f20ef
--- /dev/null
+++ b/arch/arm64/boot/dts/google/lga-b0.dts
@@ -0,0 +1,391 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Google Tensor G5 (laguna) SoC rev B0
+ *
+ * Copyright 2024-2025 Google LLC.
+ */
+
+/dts-v1/;
+
+#include <dt-bindings/interrupt-controller/arm-gic.h>
+#include <dt-bindings/interrupt-controller/irq.h>
+
+/ {
+ model = "Google Tensor G5 rev B0";
+ compatible = "google,soc-id-0005-rev-10", "google,lga";
+ #address-cells = <2>;
+ #size-cells = <2>;
+ interrupt-parent = <&gic>;
+
+ memory: memory@80000000 {
+ device_type = "memory";
+ /* We expect the bootloader to fill in the size */
+ reg = <0x00000000 0x80000000 0x00000000 0x00000000>;
+ };
+
+ reserved_memory: reserved-memory {
+ #address-cells = <2>;
+ #size-cells = <2>;
+ ranges;
+ };
+
+ cpus: cpus {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ hayes_0: cpu@0 {
+ compatible = "arm,cortex-a520";
+ reg = <0x000>;
+
+ #cooling-cells = <2>;
+ capacity-dmips-mhz = <258>;
+ device_type = "cpu";
+ enable-method = "psci";
+ power-domain-names = "psci";
+ power-domains = <&cpu_pd0>;
+ };
+
+ hayes_1: cpu@100 {
+ compatible = "arm,cortex-a520";
+ reg = <0x100>;
+
+ #cooling-cells = <2>;
+ capacity-dmips-mhz = <258>;
+ device_type = "cpu";
+ enable-method = "psci";
+ power-domain-names = "psci";
+ power-domains = <&cpu_pd1>;
+ };
+
+ hunter_0: cpu@200 {
+ compatible = "arm,cortex-a725";
+ reg = <0x200>;
+
+ #cooling-cells = <2>;
+ capacity-dmips-mhz = <891>;
+ device_type = "cpu";
+ enable-method = "psci";
+ power-domain-names = "psci";
+ power-domains = <&cpu_pd2>;
+ };
+
+ hunter_1: cpu@300 {
+ compatible = "arm,cortex-a725";
+ reg = <0x300>;
+
+ #cooling-cells = <2>;
+ capacity-dmips-mhz = <891>;
+ device_type = "cpu";
+ enable-method = "psci";
+ power-domain-names = "psci";
+ power-domains = <&cpu_pd3>;
+ };
+
+ hunter_2: cpu@400 {
+ compatible = "arm,cortex-a725";
+ reg = <0x400>;
+
+ #cooling-cells = <2>;
+ capacity-dmips-mhz = <891>;
+ device_type = "cpu";
+ enable-method = "psci";
+ power-domain-names = "psci";
+ power-domains = <&cpu_pd4>;
+ };
+
+ hunter_3: cpu@500 {
+ compatible = "arm,cortex-a725";
+ reg = <0x500>;
+
+ #cooling-cells = <2>;
+ capacity-dmips-mhz = <891>;
+ device_type = "cpu";
+ enable-method = "psci";
+ power-domain-names = "psci";
+ power-domains = <&cpu_pd5>;
+ };
+
+ hunter_4: cpu@600 {
+ compatible = "arm,cortex-a725";
+ reg = <0x600>;
+
+ #cooling-cells = <2>;
+ capacity-dmips-mhz = <891>;
+ device_type = "cpu";
+ enable-method = "psci";
+ power-domain-names = "psci";
+ power-domains = <&cpu_pd6>;
+ };
+
+ hunterelp_0: cpu@700 {
+ compatible = "arm,cortex-x4";
+ reg = <0x700>;
+
+ #cooling-cells = <2>;
+ capacity-dmips-mhz = <1024>;
+ device_type = "cpu";
+ enable-method = "psci";
+ power-domain-names = "psci";
+ power-domains = <&cpu_pd7>;
+ };
+
+ cpu-map {
+ cluster0 {
+ core0 {
+ cpu = <&hayes_0>;
+ };
+ core1 {
+ cpu = <&hayes_1>;
+ };
+ core2 {
+ cpu = <&hunter_0>;
+ };
+ core3 {
+ cpu = <&hunter_1>;
+ };
+ core4 {
+ cpu = <&hunter_2>;
+ };
+ core5 {
+ cpu = <&hunter_3>;
+ };
+ core6 {
+ cpu = <&hunter_4>;
+ };
+ core7 {
+ cpu = <&hunterelp_0>;
+ };
+ };
+ };
+
+ idle-states {
+ entry-method = "psci";
+
+ cpu_lit_c2: cpu-lit-c2 {
+ compatible = "arm,idle-state";
+
+ entry-latency-us = <132>;
+ exit-latency-us = <296>;
+ min-residency-us = <3610>;
+
+ idle-state-name = "cpu-lit-c2";
+ local-timer-stop;
+
+ arm,psci-suspend-param = <0x40000003>;
+ };
+
+ cpu_mid1_c2: cpu-mid1-c2 {
+ compatible = "arm,idle-state";
+
+ entry-latency-us = <130>;
+ exit-latency-us = <274>;
+ min-residency-us = <2720>;
+
+ idle-state-name = "cpu-mid1-c2";
+ local-timer-stop;
+
+ arm,psci-suspend-param = <0x40000003>;
+ };
+
+ cpu_mid2_c2: cpu-mid2-c2 {
+ compatible = "arm,idle-state";
+
+ entry-latency-us = <130>;
+ exit-latency-us = <274>;
+ min-residency-us = <2720>;
+
+ idle-state-name = "cpu-mid2-c2";
+ local-timer-stop;
+
+ arm,psci-suspend-param = <0x40000003>;
+ };
+
+ cpu_big_c2: cpu-big-c2 {
+ compatible = "arm,idle-state";
+
+ entry-latency-us = <110>;
+ exit-latency-us = <413>;
+ min-residency-us = <3950>;
+
+ idle-state-name = "cpu-big-c2";
+ local-timer-stop;
+
+ arm,psci-suspend-param = <0x40000003>;
+ };
+ };
+
+ domain-idle-states {
+ cluster_1_c3: cluster-1-c3 {
+ compatible = "domain-idle-state";
+
+ entry-latency-us = <325>;
+ exit-latency-us = <553>;
+ min-residency-us = <10000>;
+
+ idle-state-name = "cluster-1-c3";
+
+ arm,psci-suspend-param = <0x40010033>;
+ };
+
+ cluster_2_c3: cluster-2-c3 {
+ compatible = "domain-idle-state";
+
+ entry-latency-us = <345>;
+ exit-latency-us = <673>;
+ min-residency-us = <10000>;
+
+ idle-state-name = "cluster-2-c3";
+
+ arm,psci-suspend-param = <0x40010033>;
+ };
+
+ cluster_c4_deep: cluster-c4-deep {
+ compatible = "domain-idle-state";
+
+ entry-latency-us = <510>;
+ exit-latency-us = <1027>;
+ min-residency-us = <10000>;
+
+ idle-state-name = "cluster-c4-deep";
+
+ arm,psci-suspend-param = <0x40020333>;
+ };
+ };
+ };
+
+ psci {
+ compatible = "arm,psci-1.0";
+ method = "smc";
+
+ cpu_pd0: power-domain-cpu0 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cpu_lit_c2>;
+ power-domains = <&cpu_top_cl>;
+ };
+
+ cpu_pd1: power-domain-cpu1 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cpu_lit_c2>;
+ power-domains = <&cpu_top_cl>;
+ };
+
+ cpu_pd2: power-domain-cpu2 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cpu_mid1_c2>;
+ power-domains = <&cpucl1>;
+ };
+
+ cpu_pd3: power-domain-cpu3 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cpu_mid1_c2>;
+ power-domains = <&cpucl1>;
+ };
+
+ cpu_pd4: power-domain-cpu4 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cpu_mid1_c2>;
+ power-domains = <&cpucl1>;
+ };
+
+ cpu_pd5: power-domain-cpu5 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cpu_mid2_c2>;
+ power-domains = <&cpucl2>;
+ };
+
+ cpu_pd6: power-domain-cpu6 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cpu_mid2_c2>;
+ power-domains = <&cpucl2>;
+ };
+
+ cpu_pd7: power-domain-cpu7 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cpu_big_c2>;
+ power-domains = <&cpucl2>;
+ };
+
+ cpucl1: power-domain-cluster-1 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cluster_1_c3>;
+ power-domains = <&cpu_top_cl>;
+ };
+
+ cpucl2: power-domain-cluster-2 {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cluster_2_c3>;
+ power-domains = <&cpu_top_cl>;
+ };
+
+ cpu_top_cl: power-domain-top-cluster {
+ #power-domain-cells = <0>;
+ domain-idle-states = <&cluster_c4_deep>;
+ };
+ };
+
+ timer {
+ compatible = "arm,armv8-timer";
+ interrupts =
+ <GIC_PPI 13 (GIC_CPU_MASK_SIMPLE(1) | IRQ_TYPE_LEVEL_LOW) 0>,
+ <GIC_PPI 14 (GIC_CPU_MASK_SIMPLE(1) | IRQ_TYPE_LEVEL_LOW) 0>,
+ <GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(1) | IRQ_TYPE_LEVEL_LOW) 0>,
+ <GIC_PPI 10 (GIC_CPU_MASK_SIMPLE(1) | IRQ_TYPE_LEVEL_LOW) 0>;
+ };
+
+ /*
+ * The Pixel bootloader considers it a fatal error if it doesn't find
+ * a `ufs0` alias so it can add calibration data to the node. Until
+ * the proper UFS controller node is added under the SoC, create a
+ * temporary node to make the bootloader happy.
+ */
+ ufs: ufs-placeholder {
+ };
+
+ soc: soc@0 {
+ compatible = "simple-bus";
+ ranges = <0 0 0 0 0x10 0>;
+
+ dma-ranges = <0 0 0 0 0x10 0>;
+
+ #address-cells = <2>;
+ #size-cells = <2>;
+
+ gic: interrupt-controller@5880000 { /* TODO ask for CPU IPC CSR */
+ compatible = "arm,gic-v3";
+ reg = <0 0x05880000 0 0x00010000>,
+ <0 0x05900000 0 0x00200000>;
+ ranges;
+
+ #address-cells = <2>;
+ #size-cells = <2>;
+
+ #interrupt-cells = <4>;
+ interrupt-controller;
+ interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH 0>;
+
+ ppi-partitions {
+ ppi_cluster0: interrupt-partition-0 {
+ affinity = <&hayes_0 &hayes_1
+ &hunter_0 &hunter_1 &hunter_2
+ &hunter_3 &hunter_4>;
+ };
+
+ ppi_cluster1: interrupt-partition-1 {
+ affinity = <&hunterelp_0>;
+ };
+ };
+ };
+
+ lsion_cli16_uart: serial@db62000 {
+ compatible = "google,lga-uart", "snps,dw-apb-uart";
+ reg = <0 0x0db62000 0 0x100>;
+
+ clock-frequency = <200000000>;
+ interrupts = <GIC_SPI 688 IRQ_TYPE_LEVEL_HIGH 0>;
+ reg-io-width = <4>;
+ reg-shift = <2>;
+
+ status = "disabled";
+ };
+ };
+};
diff --git a/arch/arm64/boot/dts/google/lga-blazer-mp1.dtso b/arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
new file mode 100644
index 000000000000..1c0248b931e8
--- /dev/null
+++ b/arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Google Pixel 10 Pro (blazer) MP 1
+ *
+ * Copyright 2024-2025 Google LLC.
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include "lga-muzel-common.dtsi"
+
+/ {
+ board-id = <0x070406>;
+ board-rev = <0x010000>;
+};
+
+&{/} {
+ model = "BLAZER MP 1 based on LGA";
+ compatible = "google,pixel-id-070406-rev-010000",
+ "google,lga-blazer", "google,lga";
+};
diff --git a/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
new file mode 100644
index 000000000000..133494de7a9b
--- /dev/null
+++ b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Google Pixel 10 (frankel) MP 1
+ *
+ * Copyright 2024-2025 Google LLC.
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include "lga-muzel-common.dtsi"
+
+/ {
+ board-id = <0x070306>;
+ board-rev = <0x010000>;
+};
+
+&{/} {
+ model = "FRANKEL MP 1 based on LGA";
+ compatible = "google,pixel-id-070306-rev-010000",
+ "google,lga-frankel", "google,lga";
+};
diff --git a/arch/arm64/boot/dts/google/lga-mustang-mp1.dtso b/arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
new file mode 100644
index 000000000000..1f79bbe48056
--- /dev/null
+++ b/arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Google Pixel 10 Pro XL (mustang) MP 1
+ *
+ * Copyright 2024-2025 Google LLC.
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include "lga-muzel-common.dtsi"
+
+/ {
+ board-id = <0x070506>;
+ board-rev = <0x010000>;
+};
+
+&{/} {
+ model = "MUSTANG MP 1 based on LGA";
+ compatible = "google,pixel-id-070506-rev-010000",
+ "google,lga-mustang", "google,lga";
+};
diff --git a/arch/arm64/boot/dts/google/lga-muzel-common.dtsi b/arch/arm64/boot/dts/google/lga-muzel-common.dtsi
new file mode 100644
index 000000000000..3505f02f5b36
--- /dev/null
+++ b/arch/arm64/boot/dts/google/lga-muzel-common.dtsi
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Google Pixel 10 family (mustang + blazer + frankel = muzel) common dtsi.
+ *
+ * Copyright 2024-2025 Google LLC.
+ */
+
+&{/} {
+ chosen {
+ stdout-path = "serial0";
+ };
+
+ aliases {
+ serial0 = "/soc@0/serial@db62000"; /* &lsion_cli16_uart */
+ ufs0 = "/ufs-placeholder"; /* &ufs - TODO "/soc@0/ufs@3c400000" */
+ };
+};
--
2.51.2.1041.gc1ab5b90ca-googOn 11/11/2025 20:22, Douglas Anderson wrote:
> Add barebones device trees for frankel (Pixel 10), blazer (Pixel 10
> Pro), and mustang (Pixel 10 Pro XL). These device trees are enough to
> boot to a serial prompt using an initramfs.
>
> Many things can be noted about these device trees:
>
> 1. They are organized as "dts" files for the main SoC and "dtso"
> overlays for the boards. There is discussion about this in the
> bindings patch ("dt-bindings: arm: google: Add bindings for
> frankel/blazer/mustang").
> 2. They won't boot with the currently shipping bootloader. The current
> bootloader hardcodes several paths to nodes that it wants to update
> and considers it a fatal error if it can't find these nodes.
> Interested parties will need to wait for fixes to land and a new
> bootloader to be rolled out before attempting to use these.
> 3. They only add one revision (MP1) of each of frankel, blazer, and
> mustang. With this simple barebones device tree, there doesn't
> appear to be any difference between the revisions. More revisions
> will be added as needed in the future. The heuristics in the
> bootloader will pick the MP1 device tree if there are not any
> better matches.
> 4. They only add the dts for the B0 SoC for now. The A0 SoC support
> can be added later if we find the need.
> 5. Even newer versions of the bootloader will still error out if they
> don't find a UFS node to add calibration data to. Until UFS is
> supported, we provide a bogus UFS node for the bootloader. While
> the bootloader could be changed, there is no long-term benefit
> since eventually the device tree will have a UFS node.
> 6. They purposely choose to use the full 64-bit address and size cells
> for the root node and the `soc@0` node. Although I haven't tested
> the need for this, I presume the arguments made in commit
> bede7d2dc8f3 ("arm64: dts: qcom: sdm845: Increase address and size
> cells for soc") would apply here.
> 7. Though it looks as if the UART is never enabled, the bootloader
> knows to enable the UART when the console is turned on. Baud rate
> is configurable in the bootloader so is never hardcoded in the
> device tree.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> To avoid fragmenting the discussion, IMO:
> * Let's have the discussion about using the "dts" for SoC and the
> "dtso" for the boards in response to the bindings (patch #1).
That's discussion here, bindings are irrelevant to this.
> * If we want to have a discussion about putting "board-id" and
> "model-id" at the root of the board overlays, we can have it
> here. I'll preemptively note that the "board-id" and "model-id"
> won't show up in the final combined device tree and they are just
> used by the tool (mkdtimg). We could change mkdtimg to parse the
> "compatible" strings of the overlays files (since I've put the IDs
> there too), but official the docs [1] seem to indicate that
> top-level properties like this are OK.
>
> In order for these device trees to pass validation without warnings,
> it's assumed you have my dtc patches:
> * https://lore.kernel.org/r/20251110204529.2838248-1-dianders@chromium.org
> * https://lore.kernel.org/r/20251110204529.2838248-2-dianders@chromium.org
>
> [1] https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-object-internal.txt?h=main
>
> arch/arm64/boot/dts/google/Makefile | 9 +
> arch/arm64/boot/dts/google/lga-b0.dts | 391 ++++++++++++++++++
> .../arm64/boot/dts/google/lga-blazer-mp1.dtso | 22 +
> .../boot/dts/google/lga-frankel-mp1.dtso | 22 +
> .../boot/dts/google/lga-mustang-mp1.dtso | 22 +
> .../boot/dts/google/lga-muzel-common.dtsi | 17 +
> 6 files changed, 483 insertions(+)
> create mode 100644 arch/arm64/boot/dts/google/lga-b0.dts
> create mode 100644 arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
> create mode 100644 arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> create mode 100644 arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
> create mode 100644 arch/arm64/boot/dts/google/lga-muzel-common.dtsi
>
> diff --git a/arch/arm64/boot/dts/google/Makefile b/arch/arm64/boot/dts/google/Makefile
> index a6b187e2d631..276001e91632 100644
> --- a/arch/arm64/boot/dts/google/Makefile
> +++ b/arch/arm64/boot/dts/google/Makefile
> @@ -1 +1,10 @@
> # SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
> +
> +dtb-$(CONFIG_ARCH_GOOGLE) += \
> + lga-blazer-mp1.dtb \
> + lga-frankel-mp1.dtb \
> + lga-mustang-mp1.dtb
> +
> +lga-blazer-mp1-dtbs := lga-b0.dtb lga-blazer-mp1.dtbo
> +lga-frankel-mp1-dtbs := lga-b0.dtb lga-frankel-mp1.dtbo
> +lga-mustang-mp1-dtbs := lga-b0.dtb lga-mustang-mp1.dtbo
> diff --git a/arch/arm64/boot/dts/google/lga-b0.dts b/arch/arm64/boot/dts/google/lga-b0.dts
> new file mode 100644
> index 000000000000..83c2db4f20ef
> --- /dev/null
> +++ b/arch/arm64/boot/dts/google/lga-b0.dts
> @@ -0,0 +1,391 @@
> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> +/*
> + * Google Tensor G5 (laguna) SoC rev B0
> + *
> + * Copyright 2024-2025 Google LLC.
> + */
> +
> +/dts-v1/;
> +
> +#include <dt-bindings/interrupt-controller/arm-gic.h>
> +#include <dt-bindings/interrupt-controller/irq.h>
> +
> +/ {
> + model = "Google Tensor G5 rev B0";
> + compatible = "google,soc-id-0005-rev-10", "google,lga";
So that's SoC, thus must not be a DTS file, but DTSI.
...
...
> diff --git a/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> new file mode 100644
> index 000000000000..133494de7a9b
> --- /dev/null
> +++ b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
And that's a board, so DTS.
> @@ -0,0 +1,22 @@
> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> +/*
> + * Google Pixel 10 (frankel) MP 1
> + *
> + * Copyright 2024-2025 Google LLC.
> + */
> +
> +/dts-v1/;
> +/plugin/;
> +
> +#include "lga-muzel-common.dtsi"
> +
> +/ {
> + board-id = <0x070306>;
> + board-rev = <0x010000>;
Undocumented ABI, which you cannot document because these properties are
not allowed. You cannot have them.
Best regards,
Krzysztof
On Wed, Nov 12, 2025 at 4:14 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On 11/11/2025 20:22, Douglas Anderson wrote:
> > Add barebones device trees for frankel (Pixel 10), blazer (Pixel 10
> > Pro), and mustang (Pixel 10 Pro XL). These device trees are enough to
> > boot to a serial prompt using an initramfs.
> >
> > Many things can be noted about these device trees:
> >
> > 1. They are organized as "dts" files for the main SoC and "dtso"
> > overlays for the boards. There is discussion about this in the
> > bindings patch ("dt-bindings: arm: google: Add bindings for
> > frankel/blazer/mustang").
> > 2. They won't boot with the currently shipping bootloader. The current
> > bootloader hardcodes several paths to nodes that it wants to update
> > and considers it a fatal error if it can't find these nodes.
> > Interested parties will need to wait for fixes to land and a new
> > bootloader to be rolled out before attempting to use these.
> > 3. They only add one revision (MP1) of each of frankel, blazer, and
> > mustang. With this simple barebones device tree, there doesn't
> > appear to be any difference between the revisions. More revisions
> > will be added as needed in the future. The heuristics in the
> > bootloader will pick the MP1 device tree if there are not any
> > better matches.
> > 4. They only add the dts for the B0 SoC for now. The A0 SoC support
> > can be added later if we find the need.
> > 5. Even newer versions of the bootloader will still error out if they
> > don't find a UFS node to add calibration data to. Until UFS is
> > supported, we provide a bogus UFS node for the bootloader. While
> > the bootloader could be changed, there is no long-term benefit
> > since eventually the device tree will have a UFS node.
> > 6. They purposely choose to use the full 64-bit address and size cells
> > for the root node and the `soc@0` node. Although I haven't tested
> > the need for this, I presume the arguments made in commit
> > bede7d2dc8f3 ("arm64: dts: qcom: sdm845: Increase address and size
> > cells for soc") would apply here.
> > 7. Though it looks as if the UART is never enabled, the bootloader
> > knows to enable the UART when the console is turned on. Baud rate
> > is configurable in the bootloader so is never hardcoded in the
> > device tree.
> >
> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
> > ---
> > To avoid fragmenting the discussion, IMO:
> > * Let's have the discussion about using the "dts" for SoC and the
> > "dtso" for the boards in response to the bindings (patch #1).
>
> That's discussion here, bindings are irrelevant to this.
>
> > * If we want to have a discussion about putting "board-id" and
> > "model-id" at the root of the board overlays, we can have it
> > here. I'll preemptively note that the "board-id" and "model-id"
> > won't show up in the final combined device tree and they are just
> > used by the tool (mkdtimg). We could change mkdtimg to parse the
> > "compatible" strings of the overlays files (since I've put the IDs
> > there too), but official the docs [1] seem to indicate that
> > top-level properties like this are OK.
> >
> > In order for these device trees to pass validation without warnings,
> > it's assumed you have my dtc patches:
> > * https://lore.kernel.org/r/20251110204529.2838248-1-dianders@chromium.org
> > * https://lore.kernel.org/r/20251110204529.2838248-2-dianders@chromium.org
> >
> > [1] https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-object-internal.txt?h=main
> >
> > arch/arm64/boot/dts/google/Makefile | 9 +
> > arch/arm64/boot/dts/google/lga-b0.dts | 391 ++++++++++++++++++
> > .../arm64/boot/dts/google/lga-blazer-mp1.dtso | 22 +
> > .../boot/dts/google/lga-frankel-mp1.dtso | 22 +
> > .../boot/dts/google/lga-mustang-mp1.dtso | 22 +
> > .../boot/dts/google/lga-muzel-common.dtsi | 17 +
> > 6 files changed, 483 insertions(+)
> > create mode 100644 arch/arm64/boot/dts/google/lga-b0.dts
> > create mode 100644 arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
> > create mode 100644 arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> > create mode 100644 arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
> > create mode 100644 arch/arm64/boot/dts/google/lga-muzel-common.dtsi
> >
> > diff --git a/arch/arm64/boot/dts/google/Makefile b/arch/arm64/boot/dts/google/Makefile
> > index a6b187e2d631..276001e91632 100644
> > --- a/arch/arm64/boot/dts/google/Makefile
> > +++ b/arch/arm64/boot/dts/google/Makefile
> > @@ -1 +1,10 @@
> > # SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
> > +
> > +dtb-$(CONFIG_ARCH_GOOGLE) += \
> > + lga-blazer-mp1.dtb \
> > + lga-frankel-mp1.dtb \
> > + lga-mustang-mp1.dtb
> > +
> > +lga-blazer-mp1-dtbs := lga-b0.dtb lga-blazer-mp1.dtbo
> > +lga-frankel-mp1-dtbs := lga-b0.dtb lga-frankel-mp1.dtbo
> > +lga-mustang-mp1-dtbs := lga-b0.dtb lga-mustang-mp1.dtbo
> > diff --git a/arch/arm64/boot/dts/google/lga-b0.dts b/arch/arm64/boot/dts/google/lga-b0.dts
> > new file mode 100644
> > index 000000000000..83c2db4f20ef
> > --- /dev/null
> > +++ b/arch/arm64/boot/dts/google/lga-b0.dts
> > @@ -0,0 +1,391 @@
> > +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> > +/*
> > + * Google Tensor G5 (laguna) SoC rev B0
> > + *
> > + * Copyright 2024-2025 Google LLC.
> > + */
> > +
> > +/dts-v1/;
> > +
> > +#include <dt-bindings/interrupt-controller/arm-gic.h>
> > +#include <dt-bindings/interrupt-controller/irq.h>
> > +
> > +/ {
> > + model = "Google Tensor G5 rev B0";
> > + compatible = "google,soc-id-0005-rev-10", "google,lga";
>
> So that's SoC, thus must not be a DTS file, but DTSI.
>
> ...
>
>
> ...
>
>
> > diff --git a/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> > new file mode 100644
> > index 000000000000..133494de7a9b
> > --- /dev/null
> > +++ b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
>
> And that's a board, so DTS.
>
> > @@ -0,0 +1,22 @@
> > +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> > +/*
> > + * Google Pixel 10 (frankel) MP 1
> > + *
> > + * Copyright 2024-2025 Google LLC.
> > + */
> > +
> > +/dts-v1/;
> > +/plugin/;
> > +
> > +#include "lga-muzel-common.dtsi"
> > +
> > +/ {
> > + board-id = <0x070306>;
> > + board-rev = <0x010000>;
>
> Undocumented ABI, which you cannot document because these properties are
> not allowed. You cannot have them.
This is part of the discussion I want to have at Plumbers. But I suppose
we can start here.
The Android DTB partition format uses six 32-bit integers for matching,
as opposed to a compatible string used in FIT images. Two of the integers
are the "id" and "rev" numbers in the example above. The remaining four
are custom and left up to the (vendor) bootloader implementation.
The values for these fields need to be stored somewhere with the .dts.
The compiled DTB is useless if the user cannot build a proper image for
the bootloader to consume, and that involves putting in the right numbers
in these fields. The android "mkdtimg" tool can either take the values
from some known properties within the DTB, or have them fed to it
externally.
So if we don't want these numbers in the dts itself, then we should come
up with some format to store them beside the dts files.
On a similar note, we would have a similar problem with FIT images and
overlays. The FIT image format maps a (series of) compatible string(s)
to one DTB and any number of overlays. If overlays are involved, then
the compatible string cannot come from the DTB itself, and the mapping
must be stored somewhere.
ChenYu
On 12/11/2025 10:35, Chen-Yu Tsai wrote:
> On Wed, Nov 12, 2025 at 4:14 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>
>> On 11/11/2025 20:22, Douglas Anderson wrote:
>>> Add barebones device trees for frankel (Pixel 10), blazer (Pixel 10
>>> Pro), and mustang (Pixel 10 Pro XL). These device trees are enough to
>>> boot to a serial prompt using an initramfs.
>>>
>>> Many things can be noted about these device trees:
>>>
>>> 1. They are organized as "dts" files for the main SoC and "dtso"
>>> overlays for the boards. There is discussion about this in the
>>> bindings patch ("dt-bindings: arm: google: Add bindings for
>>> frankel/blazer/mustang").
>>> 2. They won't boot with the currently shipping bootloader. The current
>>> bootloader hardcodes several paths to nodes that it wants to update
>>> and considers it a fatal error if it can't find these nodes.
>>> Interested parties will need to wait for fixes to land and a new
>>> bootloader to be rolled out before attempting to use these.
>>> 3. They only add one revision (MP1) of each of frankel, blazer, and
>>> mustang. With this simple barebones device tree, there doesn't
>>> appear to be any difference between the revisions. More revisions
>>> will be added as needed in the future. The heuristics in the
>>> bootloader will pick the MP1 device tree if there are not any
>>> better matches.
>>> 4. They only add the dts for the B0 SoC for now. The A0 SoC support
>>> can be added later if we find the need.
>>> 5. Even newer versions of the bootloader will still error out if they
>>> don't find a UFS node to add calibration data to. Until UFS is
>>> supported, we provide a bogus UFS node for the bootloader. While
>>> the bootloader could be changed, there is no long-term benefit
>>> since eventually the device tree will have a UFS node.
>>> 6. They purposely choose to use the full 64-bit address and size cells
>>> for the root node and the `soc@0` node. Although I haven't tested
>>> the need for this, I presume the arguments made in commit
>>> bede7d2dc8f3 ("arm64: dts: qcom: sdm845: Increase address and size
>>> cells for soc") would apply here.
>>> 7. Though it looks as if the UART is never enabled, the bootloader
>>> knows to enable the UART when the console is turned on. Baud rate
>>> is configurable in the bootloader so is never hardcoded in the
>>> device tree.
>>>
>>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
>>> ---
>>> To avoid fragmenting the discussion, IMO:
>>> * Let's have the discussion about using the "dts" for SoC and the
>>> "dtso" for the boards in response to the bindings (patch #1).
>>
>> That's discussion here, bindings are irrelevant to this.
>>
>>> * If we want to have a discussion about putting "board-id" and
>>> "model-id" at the root of the board overlays, we can have it
>>> here. I'll preemptively note that the "board-id" and "model-id"
>>> won't show up in the final combined device tree and they are just
>>> used by the tool (mkdtimg). We could change mkdtimg to parse the
>>> "compatible" strings of the overlays files (since I've put the IDs
>>> there too), but official the docs [1] seem to indicate that
>>> top-level properties like this are OK.
>>>
>>> In order for these device trees to pass validation without warnings,
>>> it's assumed you have my dtc patches:
>>> * https://lore.kernel.org/r/20251110204529.2838248-1-dianders@chromium.org
>>> * https://lore.kernel.org/r/20251110204529.2838248-2-dianders@chromium.org
>>>
>>> [1] https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-object-internal.txt?h=main
>>>
>>> arch/arm64/boot/dts/google/Makefile | 9 +
>>> arch/arm64/boot/dts/google/lga-b0.dts | 391 ++++++++++++++++++
>>> .../arm64/boot/dts/google/lga-blazer-mp1.dtso | 22 +
>>> .../boot/dts/google/lga-frankel-mp1.dtso | 22 +
>>> .../boot/dts/google/lga-mustang-mp1.dtso | 22 +
>>> .../boot/dts/google/lga-muzel-common.dtsi | 17 +
>>> 6 files changed, 483 insertions(+)
>>> create mode 100644 arch/arm64/boot/dts/google/lga-b0.dts
>>> create mode 100644 arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
>>> create mode 100644 arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
>>> create mode 100644 arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
>>> create mode 100644 arch/arm64/boot/dts/google/lga-muzel-common.dtsi
>>>
>>> diff --git a/arch/arm64/boot/dts/google/Makefile b/arch/arm64/boot/dts/google/Makefile
>>> index a6b187e2d631..276001e91632 100644
>>> --- a/arch/arm64/boot/dts/google/Makefile
>>> +++ b/arch/arm64/boot/dts/google/Makefile
>>> @@ -1 +1,10 @@
>>> # SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
>>> +
>>> +dtb-$(CONFIG_ARCH_GOOGLE) += \
>>> + lga-blazer-mp1.dtb \
>>> + lga-frankel-mp1.dtb \
>>> + lga-mustang-mp1.dtb
>>> +
>>> +lga-blazer-mp1-dtbs := lga-b0.dtb lga-blazer-mp1.dtbo
>>> +lga-frankel-mp1-dtbs := lga-b0.dtb lga-frankel-mp1.dtbo
>>> +lga-mustang-mp1-dtbs := lga-b0.dtb lga-mustang-mp1.dtbo
>>> diff --git a/arch/arm64/boot/dts/google/lga-b0.dts b/arch/arm64/boot/dts/google/lga-b0.dts
>>> new file mode 100644
>>> index 000000000000..83c2db4f20ef
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/google/lga-b0.dts
>>> @@ -0,0 +1,391 @@
>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
>>> +/*
>>> + * Google Tensor G5 (laguna) SoC rev B0
>>> + *
>>> + * Copyright 2024-2025 Google LLC.
>>> + */
>>> +
>>> +/dts-v1/;
>>> +
>>> +#include <dt-bindings/interrupt-controller/arm-gic.h>
>>> +#include <dt-bindings/interrupt-controller/irq.h>
>>> +
>>> +/ {
>>> + model = "Google Tensor G5 rev B0";
>>> + compatible = "google,soc-id-0005-rev-10", "google,lga";
>>
>> So that's SoC, thus must not be a DTS file, but DTSI.
>>
>> ...
>>
>>
>> ...
>>
>>
>>> diff --git a/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
>>> new file mode 100644
>>> index 000000000000..133494de7a9b
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
>>
>> And that's a board, so DTS.
>>
>>> @@ -0,0 +1,22 @@
>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
>>> +/*
>>> + * Google Pixel 10 (frankel) MP 1
>>> + *
>>> + * Copyright 2024-2025 Google LLC.
>>> + */
>>> +
>>> +/dts-v1/;
>>> +/plugin/;
>>> +
>>> +#include "lga-muzel-common.dtsi"
>>> +
>>> +/ {
>>> + board-id = <0x070306>;
>>> + board-rev = <0x010000>;
>>
>> Undocumented ABI, which you cannot document because these properties are
>> not allowed. You cannot have them.
>
> This is part of the discussion I want to have at Plumbers. But I suppose
> we can start here.
Then the patch should be called RFC as not yet ready for merging. :)
>
> The Android DTB partition format uses six 32-bit integers for matching,
> as opposed to a compatible string used in FIT images. Two of the integers
> are the "id" and "rev" numbers in the example above. The remaining four
> are custom and left up to the (vendor) bootloader implementation.
>
> The values for these fields need to be stored somewhere with the .dts.
> The compiled DTB is useless if the user cannot build a proper image for
> the bootloader to consume, and that involves putting in the right numbers
> in these fields. The android "mkdtimg" tool can either take the values
> from some known properties within the DTB, or have them fed to it
> externally.
>
> So if we don't want these numbers in the dts itself, then we should come
> up with some format to store them beside the dts files.
Re-iterating comment from Rob long time ago: adding such new properties
is fine, but they must come for more than one user and be universal
across these users.
And of course the ABI needs to be documented which did not happen here.
I indeed said incorrectly that "properties are not allowed". The
properties could be allowed if we document them according to above Rob's
comment, but that did not happen.
Adding these properties per one SoC vendor is not really allowed, like
qcom,board-id and qcom,msm-id, but maybe you intend to make it generic.
>
>
> On a similar note, we would have a similar problem with FIT images and
> overlays. The FIT image format maps a (series of) compatible string(s)
> to one DTB and any number of overlays. If overlays are involved, then
> the compatible string cannot come from the DTB itself, and the mapping
> must be stored somewhere.
I recall, although cannot find now references to, a email talk on the
list saying that such overlays should have their own compatible, thus
solving this mapping problem.
Best regards,
Krzysztof
On Wed, Nov 12, 2025 at 5:49 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On 12/11/2025 10:35, Chen-Yu Tsai wrote:
> > On Wed, Nov 12, 2025 at 4:14 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>
> >> On 11/11/2025 20:22, Douglas Anderson wrote:
> >>> Add barebones device trees for frankel (Pixel 10), blazer (Pixel 10
> >>> Pro), and mustang (Pixel 10 Pro XL). These device trees are enough to
> >>> boot to a serial prompt using an initramfs.
> >>>
> >>> Many things can be noted about these device trees:
> >>>
> >>> 1. They are organized as "dts" files for the main SoC and "dtso"
> >>> overlays for the boards. There is discussion about this in the
> >>> bindings patch ("dt-bindings: arm: google: Add bindings for
> >>> frankel/blazer/mustang").
> >>> 2. They won't boot with the currently shipping bootloader. The current
> >>> bootloader hardcodes several paths to nodes that it wants to update
> >>> and considers it a fatal error if it can't find these nodes.
> >>> Interested parties will need to wait for fixes to land and a new
> >>> bootloader to be rolled out before attempting to use these.
> >>> 3. They only add one revision (MP1) of each of frankel, blazer, and
> >>> mustang. With this simple barebones device tree, there doesn't
> >>> appear to be any difference between the revisions. More revisions
> >>> will be added as needed in the future. The heuristics in the
> >>> bootloader will pick the MP1 device tree if there are not any
> >>> better matches.
> >>> 4. They only add the dts for the B0 SoC for now. The A0 SoC support
> >>> can be added later if we find the need.
> >>> 5. Even newer versions of the bootloader will still error out if they
> >>> don't find a UFS node to add calibration data to. Until UFS is
> >>> supported, we provide a bogus UFS node for the bootloader. While
> >>> the bootloader could be changed, there is no long-term benefit
> >>> since eventually the device tree will have a UFS node.
> >>> 6. They purposely choose to use the full 64-bit address and size cells
> >>> for the root node and the `soc@0` node. Although I haven't tested
> >>> the need for this, I presume the arguments made in commit
> >>> bede7d2dc8f3 ("arm64: dts: qcom: sdm845: Increase address and size
> >>> cells for soc") would apply here.
> >>> 7. Though it looks as if the UART is never enabled, the bootloader
> >>> knows to enable the UART when the console is turned on. Baud rate
> >>> is configurable in the bootloader so is never hardcoded in the
> >>> device tree.
> >>>
> >>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> >>> ---
> >>> To avoid fragmenting the discussion, IMO:
> >>> * Let's have the discussion about using the "dts" for SoC and the
> >>> "dtso" for the boards in response to the bindings (patch #1).
> >>
> >> That's discussion here, bindings are irrelevant to this.
> >>
> >>> * If we want to have a discussion about putting "board-id" and
> >>> "model-id" at the root of the board overlays, we can have it
> >>> here. I'll preemptively note that the "board-id" and "model-id"
> >>> won't show up in the final combined device tree and they are just
> >>> used by the tool (mkdtimg). We could change mkdtimg to parse the
> >>> "compatible" strings of the overlays files (since I've put the IDs
> >>> there too), but official the docs [1] seem to indicate that
> >>> top-level properties like this are OK.
> >>>
> >>> In order for these device trees to pass validation without warnings,
> >>> it's assumed you have my dtc patches:
> >>> * https://lore.kernel.org/r/20251110204529.2838248-1-dianders@chromium.org
> >>> * https://lore.kernel.org/r/20251110204529.2838248-2-dianders@chromium.org
> >>>
> >>> [1] https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-object-internal.txt?h=main
> >>>
> >>> arch/arm64/boot/dts/google/Makefile | 9 +
> >>> arch/arm64/boot/dts/google/lga-b0.dts | 391 ++++++++++++++++++
> >>> .../arm64/boot/dts/google/lga-blazer-mp1.dtso | 22 +
> >>> .../boot/dts/google/lga-frankel-mp1.dtso | 22 +
> >>> .../boot/dts/google/lga-mustang-mp1.dtso | 22 +
> >>> .../boot/dts/google/lga-muzel-common.dtsi | 17 +
> >>> 6 files changed, 483 insertions(+)
> >>> create mode 100644 arch/arm64/boot/dts/google/lga-b0.dts
> >>> create mode 100644 arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
> >>> create mode 100644 arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> >>> create mode 100644 arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
> >>> create mode 100644 arch/arm64/boot/dts/google/lga-muzel-common.dtsi
> >>>
> >>> diff --git a/arch/arm64/boot/dts/google/Makefile b/arch/arm64/boot/dts/google/Makefile
> >>> index a6b187e2d631..276001e91632 100644
> >>> --- a/arch/arm64/boot/dts/google/Makefile
> >>> +++ b/arch/arm64/boot/dts/google/Makefile
> >>> @@ -1 +1,10 @@
> >>> # SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
> >>> +
> >>> +dtb-$(CONFIG_ARCH_GOOGLE) += \
> >>> + lga-blazer-mp1.dtb \
> >>> + lga-frankel-mp1.dtb \
> >>> + lga-mustang-mp1.dtb
> >>> +
> >>> +lga-blazer-mp1-dtbs := lga-b0.dtb lga-blazer-mp1.dtbo
> >>> +lga-frankel-mp1-dtbs := lga-b0.dtb lga-frankel-mp1.dtbo
> >>> +lga-mustang-mp1-dtbs := lga-b0.dtb lga-mustang-mp1.dtbo
> >>> diff --git a/arch/arm64/boot/dts/google/lga-b0.dts b/arch/arm64/boot/dts/google/lga-b0.dts
> >>> new file mode 100644
> >>> index 000000000000..83c2db4f20ef
> >>> --- /dev/null
> >>> +++ b/arch/arm64/boot/dts/google/lga-b0.dts
> >>> @@ -0,0 +1,391 @@
> >>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> >>> +/*
> >>> + * Google Tensor G5 (laguna) SoC rev B0
> >>> + *
> >>> + * Copyright 2024-2025 Google LLC.
> >>> + */
> >>> +
> >>> +/dts-v1/;
> >>> +
> >>> +#include <dt-bindings/interrupt-controller/arm-gic.h>
> >>> +#include <dt-bindings/interrupt-controller/irq.h>
> >>> +
> >>> +/ {
> >>> + model = "Google Tensor G5 rev B0";
> >>> + compatible = "google,soc-id-0005-rev-10", "google,lga";
> >>
> >> So that's SoC, thus must not be a DTS file, but DTSI.
> >>
> >> ...
> >>
> >>
> >> ...
> >>
> >>
> >>> diff --git a/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> >>> new file mode 100644
> >>> index 000000000000..133494de7a9b
> >>> --- /dev/null
> >>> +++ b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> >>
> >> And that's a board, so DTS.
> >>
> >>> @@ -0,0 +1,22 @@
> >>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> >>> +/*
> >>> + * Google Pixel 10 (frankel) MP 1
> >>> + *
> >>> + * Copyright 2024-2025 Google LLC.
> >>> + */
> >>> +
> >>> +/dts-v1/;
> >>> +/plugin/;
> >>> +
> >>> +#include "lga-muzel-common.dtsi"
> >>> +
> >>> +/ {
> >>> + board-id = <0x070306>;
> >>> + board-rev = <0x010000>;
> >>
> >> Undocumented ABI, which you cannot document because these properties are
> >> not allowed. You cannot have them.
> >
> > This is part of the discussion I want to have at Plumbers. But I suppose
> > we can start here.
>
> Then the patch should be called RFC as not yet ready for merging. :)
>
> >
> > The Android DTB partition format uses six 32-bit integers for matching,
> > as opposed to a compatible string used in FIT images. Two of the integers
> > are the "id" and "rev" numbers in the example above. The remaining four
> > are custom and left up to the (vendor) bootloader implementation.
> >
> > The values for these fields need to be stored somewhere with the .dts.
> > The compiled DTB is useless if the user cannot build a proper image for
> > the bootloader to consume, and that involves putting in the right numbers
> > in these fields. The android "mkdtimg" tool can either take the values
> > from some known properties within the DTB, or have them fed to it
> > externally.
> >
> > So if we don't want these numbers in the dts itself, then we should come
> > up with some format to store them beside the dts files.
>
> Re-iterating comment from Rob long time ago: adding such new properties
> is fine, but they must come for more than one user and be universal
> across these users.
Is Android universal enough? As mentioned above, Android defines some
fields that it wants in its DTBO partition header. I am doubtful we
could generalize further, since each bootloader scheme wants different
things.
> And of course the ABI needs to be documented which did not happen here.
>
> I indeed said incorrectly that "properties are not allowed". The
> properties could be allowed if we document them according to above Rob's
> comment, but that did not happen.
>
> Adding these properties per one SoC vendor is not really allowed, like
> qcom,board-id and qcom,msm-id, but maybe you intend to make it generic.
That is indeed not great. I believe this part predates the DTBO partition
format, and is also related to how vendors split their base DTB and
overlays, such as the scheme Doug presented.
Maybe the new Android Generic Boot Loader (GBL) work will provide
unification. I will reach out to them to see what's happening in that space.
> > On a similar note, we would have a similar problem with FIT images and
> > overlays. The FIT image format maps a (series of) compatible string(s)
> > to one DTB and any number of overlays. If overlays are involved, then
> > the compatible string cannot come from the DTB itself, and the mapping
> > must be stored somewhere.
>
> I recall, although cannot find now references to, a email talk on the
> list saying that such overlays should have their own compatible, thus
> solving this mapping problem.
Rob provided it in the other thread. The per-overlay compatible allows
identifying the overlay instead of using the filename, which I think
is much appreciated. But we still need a mapping of what a final device
compatible breaks down to.
For example, say we have the the following:
- product common base "google,yoda" (DTB)
- codec option one "google,yoda-codec-rt5682i" (DTBO)
- codec option two "google,yoda-codec-rt5682s" (DTBO)
- WWAN module and SAR sensor option "google,yoda,wwan" (DTBO)
We then have different SKUs that are a combination of the above:
- product SKU "google,yoda-sku0"
combine "google,yoda", "google,yoda-codec-rt5682s", and "google,yoda,wwan"
- product SKU "google,yoda-sku4"
combine "google,yoda", "google,yoda-codec-rt5682i", and "google,yoda,wwan"
- product SKU "google,yoda-sku16"
combine "google,yoda" and "google,yoda-codec-rt5682s"
This is the mapping we have to put _somewhere_. The bootloader only
knows about "google,yoda-skuXYZ" and "google,yoda", as described in
the Chromebook boot flow document [1].
Now I suppose we could have per-SKU DTBOs that just update the base
compatible string, and have Makefile rules put them all together.
But we have something like 32 SKUs just for this product alone, and
I don't think we want to add that many dtso files. The whole reason
for us to switch to overlays was to avoid the explosion of SKU-based
DTB files.
Thanks
ChenYu
[1] Documentation/arch/arm/google/chromebook-boot-flow.rst
On 17/11/2025 07:43, Chen-Yu Tsai wrote:
> On Wed, Nov 12, 2025 at 5:49 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>
>> On 12/11/2025 10:35, Chen-Yu Tsai wrote:
>>> On Wed, Nov 12, 2025 at 4:14 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>>
>>>> On 11/11/2025 20:22, Douglas Anderson wrote:
>>>>> Add barebones device trees for frankel (Pixel 10), blazer (Pixel 10
>>>>> Pro), and mustang (Pixel 10 Pro XL). These device trees are enough to
>>>>> boot to a serial prompt using an initramfs.
>>>>>
>>>>> Many things can be noted about these device trees:
>>>>>
>>>>> 1. They are organized as "dts" files for the main SoC and "dtso"
>>>>> overlays for the boards. There is discussion about this in the
>>>>> bindings patch ("dt-bindings: arm: google: Add bindings for
>>>>> frankel/blazer/mustang").
>>>>> 2. They won't boot with the currently shipping bootloader. The current
>>>>> bootloader hardcodes several paths to nodes that it wants to update
>>>>> and considers it a fatal error if it can't find these nodes.
>>>>> Interested parties will need to wait for fixes to land and a new
>>>>> bootloader to be rolled out before attempting to use these.
>>>>> 3. They only add one revision (MP1) of each of frankel, blazer, and
>>>>> mustang. With this simple barebones device tree, there doesn't
>>>>> appear to be any difference between the revisions. More revisions
>>>>> will be added as needed in the future. The heuristics in the
>>>>> bootloader will pick the MP1 device tree if there are not any
>>>>> better matches.
>>>>> 4. They only add the dts for the B0 SoC for now. The A0 SoC support
>>>>> can be added later if we find the need.
>>>>> 5. Even newer versions of the bootloader will still error out if they
>>>>> don't find a UFS node to add calibration data to. Until UFS is
>>>>> supported, we provide a bogus UFS node for the bootloader. While
>>>>> the bootloader could be changed, there is no long-term benefit
>>>>> since eventually the device tree will have a UFS node.
>>>>> 6. They purposely choose to use the full 64-bit address and size cells
>>>>> for the root node and the `soc@0` node. Although I haven't tested
>>>>> the need for this, I presume the arguments made in commit
>>>>> bede7d2dc8f3 ("arm64: dts: qcom: sdm845: Increase address and size
>>>>> cells for soc") would apply here.
>>>>> 7. Though it looks as if the UART is never enabled, the bootloader
>>>>> knows to enable the UART when the console is turned on. Baud rate
>>>>> is configurable in the bootloader so is never hardcoded in the
>>>>> device tree.
>>>>>
>>>>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
>>>>> ---
>>>>> To avoid fragmenting the discussion, IMO:
>>>>> * Let's have the discussion about using the "dts" for SoC and the
>>>>> "dtso" for the boards in response to the bindings (patch #1).
>>>>
>>>> That's discussion here, bindings are irrelevant to this.
>>>>
>>>>> * If we want to have a discussion about putting "board-id" and
>>>>> "model-id" at the root of the board overlays, we can have it
>>>>> here. I'll preemptively note that the "board-id" and "model-id"
>>>>> won't show up in the final combined device tree and they are just
>>>>> used by the tool (mkdtimg). We could change mkdtimg to parse the
>>>>> "compatible" strings of the overlays files (since I've put the IDs
>>>>> there too), but official the docs [1] seem to indicate that
>>>>> top-level properties like this are OK.
>>>>>
>>>>> In order for these device trees to pass validation without warnings,
>>>>> it's assumed you have my dtc patches:
>>>>> * https://lore.kernel.org/r/20251110204529.2838248-1-dianders@chromium.org
>>>>> * https://lore.kernel.org/r/20251110204529.2838248-2-dianders@chromium.org
>>>>>
>>>>> [1] https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-object-internal.txt?h=main
>>>>>
>>>>> arch/arm64/boot/dts/google/Makefile | 9 +
>>>>> arch/arm64/boot/dts/google/lga-b0.dts | 391 ++++++++++++++++++
>>>>> .../arm64/boot/dts/google/lga-blazer-mp1.dtso | 22 +
>>>>> .../boot/dts/google/lga-frankel-mp1.dtso | 22 +
>>>>> .../boot/dts/google/lga-mustang-mp1.dtso | 22 +
>>>>> .../boot/dts/google/lga-muzel-common.dtsi | 17 +
>>>>> 6 files changed, 483 insertions(+)
>>>>> create mode 100644 arch/arm64/boot/dts/google/lga-b0.dts
>>>>> create mode 100644 arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
>>>>> create mode 100644 arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
>>>>> create mode 100644 arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
>>>>> create mode 100644 arch/arm64/boot/dts/google/lga-muzel-common.dtsi
>>>>>
>>>>> diff --git a/arch/arm64/boot/dts/google/Makefile b/arch/arm64/boot/dts/google/Makefile
>>>>> index a6b187e2d631..276001e91632 100644
>>>>> --- a/arch/arm64/boot/dts/google/Makefile
>>>>> +++ b/arch/arm64/boot/dts/google/Makefile
>>>>> @@ -1 +1,10 @@
>>>>> # SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
>>>>> +
>>>>> +dtb-$(CONFIG_ARCH_GOOGLE) += \
>>>>> + lga-blazer-mp1.dtb \
>>>>> + lga-frankel-mp1.dtb \
>>>>> + lga-mustang-mp1.dtb
>>>>> +
>>>>> +lga-blazer-mp1-dtbs := lga-b0.dtb lga-blazer-mp1.dtbo
>>>>> +lga-frankel-mp1-dtbs := lga-b0.dtb lga-frankel-mp1.dtbo
>>>>> +lga-mustang-mp1-dtbs := lga-b0.dtb lga-mustang-mp1.dtbo
>>>>> diff --git a/arch/arm64/boot/dts/google/lga-b0.dts b/arch/arm64/boot/dts/google/lga-b0.dts
>>>>> new file mode 100644
>>>>> index 000000000000..83c2db4f20ef
>>>>> --- /dev/null
>>>>> +++ b/arch/arm64/boot/dts/google/lga-b0.dts
>>>>> @@ -0,0 +1,391 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
>>>>> +/*
>>>>> + * Google Tensor G5 (laguna) SoC rev B0
>>>>> + *
>>>>> + * Copyright 2024-2025 Google LLC.
>>>>> + */
>>>>> +
>>>>> +/dts-v1/;
>>>>> +
>>>>> +#include <dt-bindings/interrupt-controller/arm-gic.h>
>>>>> +#include <dt-bindings/interrupt-controller/irq.h>
>>>>> +
>>>>> +/ {
>>>>> + model = "Google Tensor G5 rev B0";
>>>>> + compatible = "google,soc-id-0005-rev-10", "google,lga";
>>>>
>>>> So that's SoC, thus must not be a DTS file, but DTSI.
>>>>
>>>> ...
>>>>
>>>>
>>>> ...
>>>>
>>>>
>>>>> diff --git a/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
>>>>> new file mode 100644
>>>>> index 000000000000..133494de7a9b
>>>>> --- /dev/null
>>>>> +++ b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
>>>>
>>>> And that's a board, so DTS.
>>>>
>>>>> @@ -0,0 +1,22 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
>>>>> +/*
>>>>> + * Google Pixel 10 (frankel) MP 1
>>>>> + *
>>>>> + * Copyright 2024-2025 Google LLC.
>>>>> + */
>>>>> +
>>>>> +/dts-v1/;
>>>>> +/plugin/;
>>>>> +
>>>>> +#include "lga-muzel-common.dtsi"
>>>>> +
>>>>> +/ {
>>>>> + board-id = <0x070306>;
>>>>> + board-rev = <0x010000>;
>>>>
>>>> Undocumented ABI, which you cannot document because these properties are
>>>> not allowed. You cannot have them.
>>>
>>> This is part of the discussion I want to have at Plumbers. But I suppose
>>> we can start here.
>>
>> Then the patch should be called RFC as not yet ready for merging. :)
>>
>>>
>>> The Android DTB partition format uses six 32-bit integers for matching,
>>> as opposed to a compatible string used in FIT images. Two of the integers
>>> are the "id" and "rev" numbers in the example above. The remaining four
>>> are custom and left up to the (vendor) bootloader implementation.
>>>
>>> The values for these fields need to be stored somewhere with the .dts.
>>> The compiled DTB is useless if the user cannot build a proper image for
>>> the bootloader to consume, and that involves putting in the right numbers
>>> in these fields. The android "mkdtimg" tool can either take the values
>>> from some known properties within the DTB, or have them fed to it
>>> externally.
>>>
>>> So if we don't want these numbers in the dts itself, then we should come
>>> up with some format to store them beside the dts files.
>>
>> Re-iterating comment from Rob long time ago: adding such new properties
>> is fine, but they must come for more than one user and be universal
>> across these users.
>
> Is Android universal enough? As mentioned above, Android defines some
> fields that it wants in its DTBO partition header. I am doubtful we
> could generalize further, since each bootloader scheme wants different
> things.
There is no such user of these bindings as "Android".
>
>> And of course the ABI needs to be documented which did not happen here.
>>
>> I indeed said incorrectly that "properties are not allowed". The
>> properties could be allowed if we document them according to above Rob's
>> comment, but that did not happen.
>>
>> Adding these properties per one SoC vendor is not really allowed, like
>> qcom,board-id and qcom,msm-id, but maybe you intend to make it generic.
>
> That is indeed not great. I believe this part predates the DTBO partition
> format, and is also related to how vendors split their base DTB and
> overlays, such as the scheme Doug presented.
>
> Maybe the new Android Generic Boot Loader (GBL) work will provide
> unification. I will reach out to them to see what's happening in that space.
>
>>> On a similar note, we would have a similar problem with FIT images and
>>> overlays. The FIT image format maps a (series of) compatible string(s)
>>> to one DTB and any number of overlays. If overlays are involved, then
>>> the compatible string cannot come from the DTB itself, and the mapping
>>> must be stored somewhere.
>>
>> I recall, although cannot find now references to, a email talk on the
>> list saying that such overlays should have their own compatible, thus
>> solving this mapping problem.
>
> Rob provided it in the other thread. The per-overlay compatible allows
> identifying the overlay instead of using the filename, which I think
> is much appreciated. But we still need a mapping of what a final device
> compatible breaks down to.
Who is "we"? Linux does not care about that mapping. For user-space
"google,yoda-sku0" should be good enough.
>
> For example, say we have the the following:
>
> - product common base "google,yoda" (DTB)
> - codec option one "google,yoda-codec-rt5682i" (DTBO)
> - codec option two "google,yoda-codec-rt5682s" (DTBO)
> - WWAN module and SAR sensor option "google,yoda,wwan" (DTBO)
>
> We then have different SKUs that are a combination of the above:
>
> - product SKU "google,yoda-sku0"
> combine "google,yoda", "google,yoda-codec-rt5682s", and "google,yoda,wwan"
>
> - product SKU "google,yoda-sku4"
> combine "google,yoda", "google,yoda-codec-rt5682i", and "google,yoda,wwan"
>
> - product SKU "google,yoda-sku16"
> combine "google,yoda" and "google,yoda-codec-rt5682s"
>
> This is the mapping we have to put _somewhere_. The bootloader only
> knows about "google,yoda-skuXYZ" and "google,yoda", as described in
> the Chromebook boot flow document [1].
>
The entire pathset is about Google Pixel so I really do not get how
Chromebook boot flow got here.
Best regards,
Krzysztof
On Mon, Nov 17, 2025 at 2:55 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On 17/11/2025 07:43, Chen-Yu Tsai wrote:
> > On Wed, Nov 12, 2025 at 5:49 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>
> >> On 12/11/2025 10:35, Chen-Yu Tsai wrote:
> >>> On Wed, Nov 12, 2025 at 4:14 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>>>
> >>>> On 11/11/2025 20:22, Douglas Anderson wrote:
> >>>>> Add barebones device trees for frankel (Pixel 10), blazer (Pixel 10
> >>>>> Pro), and mustang (Pixel 10 Pro XL). These device trees are enough to
> >>>>> boot to a serial prompt using an initramfs.
> >>>>>
> >>>>> Many things can be noted about these device trees:
> >>>>>
> >>>>> 1. They are organized as "dts" files for the main SoC and "dtso"
> >>>>> overlays for the boards. There is discussion about this in the
> >>>>> bindings patch ("dt-bindings: arm: google: Add bindings for
> >>>>> frankel/blazer/mustang").
> >>>>> 2. They won't boot with the currently shipping bootloader. The current
> >>>>> bootloader hardcodes several paths to nodes that it wants to update
> >>>>> and considers it a fatal error if it can't find these nodes.
> >>>>> Interested parties will need to wait for fixes to land and a new
> >>>>> bootloader to be rolled out before attempting to use these.
> >>>>> 3. They only add one revision (MP1) of each of frankel, blazer, and
> >>>>> mustang. With this simple barebones device tree, there doesn't
> >>>>> appear to be any difference between the revisions. More revisions
> >>>>> will be added as needed in the future. The heuristics in the
> >>>>> bootloader will pick the MP1 device tree if there are not any
> >>>>> better matches.
> >>>>> 4. They only add the dts for the B0 SoC for now. The A0 SoC support
> >>>>> can be added later if we find the need.
> >>>>> 5. Even newer versions of the bootloader will still error out if they
> >>>>> don't find a UFS node to add calibration data to. Until UFS is
> >>>>> supported, we provide a bogus UFS node for the bootloader. While
> >>>>> the bootloader could be changed, there is no long-term benefit
> >>>>> since eventually the device tree will have a UFS node.
> >>>>> 6. They purposely choose to use the full 64-bit address and size cells
> >>>>> for the root node and the `soc@0` node. Although I haven't tested
> >>>>> the need for this, I presume the arguments made in commit
> >>>>> bede7d2dc8f3 ("arm64: dts: qcom: sdm845: Increase address and size
> >>>>> cells for soc") would apply here.
> >>>>> 7. Though it looks as if the UART is never enabled, the bootloader
> >>>>> knows to enable the UART when the console is turned on. Baud rate
> >>>>> is configurable in the bootloader so is never hardcoded in the
> >>>>> device tree.
> >>>>>
> >>>>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> >>>>> ---
> >>>>> To avoid fragmenting the discussion, IMO:
> >>>>> * Let's have the discussion about using the "dts" for SoC and the
> >>>>> "dtso" for the boards in response to the bindings (patch #1).
> >>>>
> >>>> That's discussion here, bindings are irrelevant to this.
> >>>>
> >>>>> * If we want to have a discussion about putting "board-id" and
> >>>>> "model-id" at the root of the board overlays, we can have it
> >>>>> here. I'll preemptively note that the "board-id" and "model-id"
> >>>>> won't show up in the final combined device tree and they are just
> >>>>> used by the tool (mkdtimg). We could change mkdtimg to parse the
> >>>>> "compatible" strings of the overlays files (since I've put the IDs
> >>>>> there too), but official the docs [1] seem to indicate that
> >>>>> top-level properties like this are OK.
> >>>>>
> >>>>> In order for these device trees to pass validation without warnings,
> >>>>> it's assumed you have my dtc patches:
> >>>>> * https://lore.kernel.org/r/20251110204529.2838248-1-dianders@chromium.org
> >>>>> * https://lore.kernel.org/r/20251110204529.2838248-2-dianders@chromium.org
> >>>>>
> >>>>> [1] https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-object-internal.txt?h=main
> >>>>>
> >>>>> arch/arm64/boot/dts/google/Makefile | 9 +
> >>>>> arch/arm64/boot/dts/google/lga-b0.dts | 391 ++++++++++++++++++
> >>>>> .../arm64/boot/dts/google/lga-blazer-mp1.dtso | 22 +
> >>>>> .../boot/dts/google/lga-frankel-mp1.dtso | 22 +
> >>>>> .../boot/dts/google/lga-mustang-mp1.dtso | 22 +
> >>>>> .../boot/dts/google/lga-muzel-common.dtsi | 17 +
> >>>>> 6 files changed, 483 insertions(+)
> >>>>> create mode 100644 arch/arm64/boot/dts/google/lga-b0.dts
> >>>>> create mode 100644 arch/arm64/boot/dts/google/lga-blazer-mp1.dtso
> >>>>> create mode 100644 arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> >>>>> create mode 100644 arch/arm64/boot/dts/google/lga-mustang-mp1.dtso
> >>>>> create mode 100644 arch/arm64/boot/dts/google/lga-muzel-common.dtsi
> >>>>>
> >>>>> diff --git a/arch/arm64/boot/dts/google/Makefile b/arch/arm64/boot/dts/google/Makefile
> >>>>> index a6b187e2d631..276001e91632 100644
> >>>>> --- a/arch/arm64/boot/dts/google/Makefile
> >>>>> +++ b/arch/arm64/boot/dts/google/Makefile
> >>>>> @@ -1 +1,10 @@
> >>>>> # SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
> >>>>> +
> >>>>> +dtb-$(CONFIG_ARCH_GOOGLE) += \
> >>>>> + lga-blazer-mp1.dtb \
> >>>>> + lga-frankel-mp1.dtb \
> >>>>> + lga-mustang-mp1.dtb
> >>>>> +
> >>>>> +lga-blazer-mp1-dtbs := lga-b0.dtb lga-blazer-mp1.dtbo
> >>>>> +lga-frankel-mp1-dtbs := lga-b0.dtb lga-frankel-mp1.dtbo
> >>>>> +lga-mustang-mp1-dtbs := lga-b0.dtb lga-mustang-mp1.dtbo
> >>>>> diff --git a/arch/arm64/boot/dts/google/lga-b0.dts b/arch/arm64/boot/dts/google/lga-b0.dts
> >>>>> new file mode 100644
> >>>>> index 000000000000..83c2db4f20ef
> >>>>> --- /dev/null
> >>>>> +++ b/arch/arm64/boot/dts/google/lga-b0.dts
> >>>>> @@ -0,0 +1,391 @@
> >>>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> >>>>> +/*
> >>>>> + * Google Tensor G5 (laguna) SoC rev B0
> >>>>> + *
> >>>>> + * Copyright 2024-2025 Google LLC.
> >>>>> + */
> >>>>> +
> >>>>> +/dts-v1/;
> >>>>> +
> >>>>> +#include <dt-bindings/interrupt-controller/arm-gic.h>
> >>>>> +#include <dt-bindings/interrupt-controller/irq.h>
> >>>>> +
> >>>>> +/ {
> >>>>> + model = "Google Tensor G5 rev B0";
> >>>>> + compatible = "google,soc-id-0005-rev-10", "google,lga";
> >>>>
> >>>> So that's SoC, thus must not be a DTS file, but DTSI.
> >>>>
> >>>> ...
> >>>>
> >>>>
> >>>> ...
> >>>>
> >>>>
> >>>>> diff --git a/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> >>>>> new file mode 100644
> >>>>> index 000000000000..133494de7a9b
> >>>>> --- /dev/null
> >>>>> +++ b/arch/arm64/boot/dts/google/lga-frankel-mp1.dtso
> >>>>
> >>>> And that's a board, so DTS.
> >>>>
> >>>>> @@ -0,0 +1,22 @@
> >>>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
> >>>>> +/*
> >>>>> + * Google Pixel 10 (frankel) MP 1
> >>>>> + *
> >>>>> + * Copyright 2024-2025 Google LLC.
> >>>>> + */
> >>>>> +
> >>>>> +/dts-v1/;
> >>>>> +/plugin/;
> >>>>> +
> >>>>> +#include "lga-muzel-common.dtsi"
> >>>>> +
> >>>>> +/ {
> >>>>> + board-id = <0x070306>;
> >>>>> + board-rev = <0x010000>;
> >>>>
> >>>> Undocumented ABI, which you cannot document because these properties are
> >>>> not allowed. You cannot have them.
> >>>
> >>> This is part of the discussion I want to have at Plumbers. But I suppose
> >>> we can start here.
> >>
> >> Then the patch should be called RFC as not yet ready for merging. :)
> >>
> >>>
> >>> The Android DTB partition format uses six 32-bit integers for matching,
> >>> as opposed to a compatible string used in FIT images. Two of the integers
> >>> are the "id" and "rev" numbers in the example above. The remaining four
> >>> are custom and left up to the (vendor) bootloader implementation.
> >>>
> >>> The values for these fields need to be stored somewhere with the .dts.
> >>> The compiled DTB is useless if the user cannot build a proper image for
> >>> the bootloader to consume, and that involves putting in the right numbers
> >>> in these fields. The android "mkdtimg" tool can either take the values
> >>> from some known properties within the DTB, or have them fed to it
> >>> externally.
> >>>
> >>> So if we don't want these numbers in the dts itself, then we should come
> >>> up with some format to store them beside the dts files.
> >>
> >> Re-iterating comment from Rob long time ago: adding such new properties
> >> is fine, but they must come for more than one user and be universal
> >> across these users.
> >
> > Is Android universal enough? As mentioned above, Android defines some
> > fields that it wants in its DTBO partition header. I am doubtful we
> > could generalize further, since each bootloader scheme wants different
> > things.
>
> There is no such user of these bindings as "Android".
Sure, since many vendors for Android-based devices don't bother to
upstream their device trees.
> >
> >> And of course the ABI needs to be documented which did not happen here.
> >>
> >> I indeed said incorrectly that "properties are not allowed". The
> >> properties could be allowed if we document them according to above Rob's
> >> comment, but that did not happen.
> >>
> >> Adding these properties per one SoC vendor is not really allowed, like
> >> qcom,board-id and qcom,msm-id, but maybe you intend to make it generic.
> >
> > That is indeed not great. I believe this part predates the DTBO partition
> > format, and is also related to how vendors split their base DTB and
> > overlays, such as the scheme Doug presented.
> >
> > Maybe the new Android Generic Boot Loader (GBL) work will provide
> > unification. I will reach out to them to see what's happening in that space.
> >
> >>> On a similar note, we would have a similar problem with FIT images and
> >>> overlays. The FIT image format maps a (series of) compatible string(s)
> >>> to one DTB and any number of overlays. If overlays are involved, then
> >>> the compatible string cannot come from the DTB itself, and the mapping
> >>> must be stored somewhere.
> >>
> >> I recall, although cannot find now references to, a email talk on the
> >> list saying that such overlays should have their own compatible, thus
> >> solving this mapping problem.
> >
> > Rob provided it in the other thread. The per-overlay compatible allows
> > identifying the overlay instead of using the filename, which I think
> > is much appreciated. But we still need a mapping of what a final device
> > compatible breaks down to.
>
> Who is "we"? Linux does not care about that mapping. For user-space
> "google,yoda-sku0" should be good enough.
"We" as in the Chromebook team, but more broadly, any user or developer
that wants to build a generic kernel image based off of base DTBs and
overlays.
> >
> > For example, say we have the the following:
> >
> > - product common base "google,yoda" (DTB)
> > - codec option one "google,yoda-codec-rt5682i" (DTBO)
> > - codec option two "google,yoda-codec-rt5682s" (DTBO)
> > - WWAN module and SAR sensor option "google,yoda,wwan" (DTBO)
> >
> > We then have different SKUs that are a combination of the above:
> >
> > - product SKU "google,yoda-sku0"
> > combine "google,yoda", "google,yoda-codec-rt5682s", and "google,yoda,wwan"
> >
> > - product SKU "google,yoda-sku4"
> > combine "google,yoda", "google,yoda-codec-rt5682i", and "google,yoda,wwan"
> >
> > - product SKU "google,yoda-sku16"
> > combine "google,yoda" and "google,yoda-codec-rt5682s"
> >
> > This is the mapping we have to put _somewhere_. The bootloader only
> > knows about "google,yoda-skuXYZ" and "google,yoda", as described in
> > the Chromebook boot flow document [1].
> >
>
> The entire pathset is about Google Pixel so I really do not get how
> Chromebook boot flow got here.
My apologies, I should have forked the thread to make it clear my stuff
was about Chromebooks, but the discussion on overlays seemed relevant.
I'll try to work out an example and RFC patchset based on existing
ChromeOS device trees to further discuss things.
ChenYu
Hi,
On Wed, Nov 12, 2025 at 1:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> >>> To avoid fragmenting the discussion, IMO:
> >>> * Let's have the discussion about using the "dts" for SoC and the
> >>> "dtso" for the boards in response to the bindings (patch #1).
> >>
> >> That's discussion here, bindings are irrelevant to this.
Ummm, OK. In any case, I'm going to wait until our discussion in the
bindings patch about whether SoCs can be final compatibles, then if I
still think extra discussion is needed I'll respond more on this
thread.
> >>> * If we want to have a discussion about putting "board-id" and
> >>> "model-id" at the root of the board overlays, we can have it
> >>> here. I'll preemptively note that the "board-id" and "model-id"
> >>> won't show up in the final combined device tree and they are just
> >>> used by the tool (mkdtimg). We could change mkdtimg to parse the
> >>> "compatible" strings of the overlays files (since I've put the IDs
> >>> there too), but official the docs [1] seem to indicate that
> >>> top-level properties like this are OK.
> >>>
> >>> In order for these device trees to pass validation without warnings,
> >>> it's assumed you have my dtc patches:
> >>> * https://lore.kernel.org/r/20251110204529.2838248-1-dianders@chromium.org
> >>> * https://lore.kernel.org/r/20251110204529.2838248-2-dianders@chromium.org
> >>>
> >>> [1] https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-object-internal.txt?h=main
> >>> + board-id = <0x070306>;
> >>> + board-rev = <0x010000>;
> >>
> >> Undocumented ABI, which you cannot document because these properties are
> >> not allowed. You cannot have them.
> >
> > This is part of the discussion I want to have at Plumbers. But I suppose
> > we can start here.
>
> Then the patch should be called RFC as not yet ready for merging. :)
>
> >
> > The Android DTB partition format uses six 32-bit integers for matching,
> > as opposed to a compatible string used in FIT images. Two of the integers
> > are the "id" and "rev" numbers in the example above. The remaining four
> > are custom and left up to the (vendor) bootloader implementation.
> >
> > The values for these fields need to be stored somewhere with the .dts.
> > The compiled DTB is useless if the user cannot build a proper image for
> > the bootloader to consume, and that involves putting in the right numbers
> > in these fields. The android "mkdtimg" tool can either take the values
> > from some known properties within the DTB, or have them fed to it
> > externally.
> >
> > So if we don't want these numbers in the dts itself, then we should come
> > up with some format to store them beside the dts files.
>
> Re-iterating comment from Rob long time ago: adding such new properties
> is fine, but they must come for more than one user and be universal
> across these users.
>
> And of course the ABI needs to be documented which did not happen here.
>
> I indeed said incorrectly that "properties are not allowed". The
> properties could be allowed if we document them according to above Rob's
> comment, but that did not happen.
>
> Adding these properties per one SoC vendor is not really allowed, like
> qcom,board-id and qcom,msm-id, but maybe you intend to make it generic.
Perhaps you have a link to Rob's comment from a long time ago?
As per my comment "after the cut" in the original patch (see above),
for my use case, I'm OK with removing the "board-id" and "board-rev"
here. It wouldn't be terribly hard to teach my tool to parse the
top-level compatible. That being said, it would be nice to allow them
at a top-level like this. As Chen-Yu says, there are other interested
parties.
The official documentation that I referred to in my comment "after the
cut" says this about properties directly in the overlays:
```
/dts-v1/;
/plugin/; /* allow undefined references and record them */
/ {
.... /* various properties for loader use; i.e. part id etc. */
fragment@0 {
```
So properties are clearly documented to be allowed here. When I read
the above, I interpret it as the properties are "whatever the expected
loader of this overlay would find convenient".
I am more than happy to document which properties my "loader"
(mkdtimg) needs if you have some proposed place or way for me to
document them. I'm happy to do it in freeform text (or markup) for now
if that's what people would accept. Maybe that lets us get started yet
still document things while we figure out what the needs are?
> > On a similar note, we would have a similar problem with FIT images and
> > overlays. The FIT image format maps a (series of) compatible string(s)
> > to one DTB and any number of overlays. If overlays are involved, then
> > the compatible string cannot come from the DTB itself, and the mapping
> > must be stored somewhere.
>
> I recall, although cannot find now references to, a email talk on the
> list saying that such overlays should have their own compatible, thus
> solving this mapping problem.
If you have more details or if Rob wants to re-iterate his thoughts,
I'm happy to discuss.
In my mind, I'd rather this not be a "compatible" but I'm also not
dead set on that. IMO, though it can be made to work, having a
"compatible" here is sorta backwards from what we want. We faced this
issue in ChromeOS when we used the top-level "compatible" to pick the
device tree. Specifically, the normal usage of "compatible" is to
start with the device tree which has a list of compatible strings.
From there, we pick a driver that matches. AKA: we start with some
"compatible" strings and find a matching "thing" (a driver). When
using a "compatible" to pick an overlay / device tree, we start with a
"thing" (a known board) and then pick a list of "compatible" strings
that matches it. Hopefully it's clear how that's a bit different.
As I said, the problems are mostly subtle, but this is how we ended up
with the weirdness on Chromebooks where we had a pile of all equal
"compatible" strings at the top level and that made all the DT folks
grumpy. See, for instance, the sc7180-trogdor-lazor-r1.dts file where
"google,lazor-rev1" and "google,lazor-rev2" are both there. We'll pick
this same DTS for both revisions.
It can be made to work, but IMO it's not a perfect fit.
I'd rather us just pick some standard property that documents the
information that the expected loader should need. Maybe you could even
handle more than one loader type?
/ {
loaders {
mkdtimg {
board-id = <0x1234>;
board-rev = <0x5678>;
};
other-loader {
something-else <0xaaaa>;
};
};
Then under the "loaders" node we have node names that need to match
exactly for various loaders and then properties that they need.
I haven't tested this, but I believe that since the "loaders" isn't
under any "fragment" that it will just be ignored when the overlay is
applied, so it will just be for the consumption of the loader.
-Doug
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