Users report being able to boot (u-boot) from SD card but kernel
init then fails to mount partitions on the card containing boot
media resulting in first-boot failure. System logs show only the
probe of the mmc devices: the SD card is seen, but no partitions
are found so init fails to mount them and boot stalls.

Reducing the speed of the SD card from 50MHz to 35MHz results in
complete probing of the card and successful boot.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
---
The same workaround of dropping to 35MHz is also done with the
ac2xx dtsi; which has a comment about CRC errors being seen at
50MHz. It's probable this is the same although I forget now how
that diagnosis was done (or who did it, Martin perhaps?). I've
removed the FIXUP comment and added one about boot failures
being seen at 50Mhz but if you prefer to repeat the CRC comment
from ac2xx feel free to fixup when applying or I can send a v2
with that change. Links to original issue reports with user test
results [0] [1] are below:

[0] https://github.com/LibreELEC/LibreELEC.tv/issues/10027
[1] https://github.com/libretro/Lakka-LibreELEC/issues/2059

 arch/arm64/boot/dts/amlogic/meson-sm1-bananapi.dtsi | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/boot/dts/amlogic/meson-sm1-bananapi.dtsi b/arch/arm64/boot/dts/amlogic/meson-sm1-bananapi.dtsi
index 40db95f64636..03b4b414cd5f 100644
--- a/arch/arm64/boot/dts/amlogic/meson-sm1-bananapi.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-sm1-bananapi.dtsi
@@ -384,11 +384,10 @@ &sd_emmc_b {
 
 	bus-width = <4>;
 	cap-sd-highspeed;
-	max-frequency = <50000000>;
+	/* Boot failures are observed at 50MHz */
+	max-frequency = <35000000>;
 	disable-wp;
 
-	/* TOFIX: SD card is barely usable in SDR modes */
-
 	cd-gpios = <&gpio GPIOC_6 GPIO_ACTIVE_LOW>;
 	vmmc-supply = <&tflash_vdd>;
 	vqmmc-supply = <&vddio_c>;
-- 
2.34.1

Hi,

On Mon, 05 May 2025 14:37:00 +0000, Christian Hewitt wrote:
> Users report being able to boot (u-boot) from SD card but kernel
> init then fails to mount partitions on the card containing boot
> media resulting in first-boot failure. System logs show only the
> probe of the mmc devices: the SD card is seen, but no partitions
> are found so init fails to mount them and boot stalls.
> 
> Reducing the speed of the SD card from 50MHz to 35MHz results in
> complete probing of the card and successful boot.
> 
> [...]

Thanks, Applied to https://git.kernel.org/pub/scm/linux/kernel/git/amlogic/linux.git (v6.18/arm64-dt)

[1/1] arm64: dts: amlogic: sm1-bananapi: lower SD card speed for stability
      https://git.kernel.org/amlogic/c/916fa558cb27182933fdfe82d6d84b437e69349c

These changes has been applied on the intermediate git tree [1].

The v6.18/arm64-dt branch will then be sent via a formal Pull Request to the Linux SoC maintainers
for inclusion in their intermediate git branches in order to be sent to Linus during
the next merge window, or sooner if it's a set of fixes.

In the cases of fixes, those will be merged in the current release candidate
kernel and as soon they appear on the Linux master branch they will be
backported to the previous Stable and Long-Stable kernels [2].

The intermediate git branches are merged daily in the linux-next tree [3],
people are encouraged testing these pre-release kernels and report issues on the
relevant mailing-lists.

If problems are discovered on those changes, please submit a signed-off-by revert
patch followed by a corrective changeset.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/amlogic/linux.git
[2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
[3] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git

-- 
Neil

On Mon, May 5, 2025 at 4:37 PM Christian Hewitt
<christianshewitt@gmail.com> wrote:
>
> Users report being able to boot (u-boot) from SD card but kernel
> init then fails to mount partitions on the card containing boot
> media resulting in first-boot failure. System logs show only the
> probe of the mmc devices: the SD card is seen, but no partitions
> are found so init fails to mount them and boot stalls.
>
> Reducing the speed of the SD card from 50MHz to 35MHz results in
> complete probing of the card and successful boot.
>
> Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

> ---
> The same workaround of dropping to 35MHz is also done with the
> ac2xx dtsi; which has a comment about CRC errors being seen at
> 50MHz. It's probable this is the same although I forget now how
> that diagnosis was done (or who did it, Martin perhaps?).
Maybe Jerome helped investigate/debug? I can't recall and at the same
time: if it fixes the end user experience it's a win.

On Tue, May 6, 2025 at 2:26 AM Martin Blumenstingl
<martin.blumenstingl@googlemail.com> wrote:
>
> On Mon, May 5, 2025 at 4:37 PM Christian Hewitt
> <christianshewitt@gmail.com> wrote:
> >
> > Users report being able to boot (u-boot) from SD card but kernel
> > init then fails to mount partitions on the card containing boot
> > media resulting in first-boot failure. System logs show only the
> > probe of the mmc devices: the SD card is seen, but no partitions
> > are found so init fails to mount them and boot stalls.
> >
> > Reducing the speed of the SD card from 50MHz to 35MHz results in
> > complete probing of the card and successful boot.
> >
> > Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
> Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
>
> > ---
> > The same workaround of dropping to 35MHz is also done with the
> > ac2xx dtsi; which has a comment about CRC errors being seen at
> > 50MHz. It's probable this is the same although I forget now how
> > that diagnosis was done (or who did it, Martin perhaps?).
> Maybe Jerome helped investigate/debug? I can't recall and at the same
> time: if it fixes the end user experience it's a win.

We had an issue too and ended up disabling MMC_MODE_HS_52MHz | MMC_MODE_HS;

>
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