arm64: dts: qcom: sdm845: Fix slimbam num-channels/ees

[PATCH] arm64: dts: qcom: sdm845: Fix slimbam num-channels/ees

Posted by Stephan Gerhold 1 month, 1 week ago

Reading the hardware registers of the &slimbam on RB3 reveals that the BAM
supports only 23 pipes (channels) and supports 4 EEs instead of 2. This
hasn't caused problems so far since nothing is using the extra channels,
but attempting to use them would lead to crashes.

The bam_dma driver might warn in the future if the num-channels in the DT
are wrong, so correct the properties in the DT to avoid future regressions.

Cc: stable@vger.kernel.org
Fixes: 27ca1de07dc3 ("arm64: dts: qcom: sdm845: add slimbus nodes")
Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
---
 arch/arm64/boot/dts/qcom/sdm845.dtsi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/sdm845.dtsi b/arch/arm64/boot/dts/qcom/sdm845.dtsi
index 828b55cb6baf10458feae8f53c04663ef958601e..02536114edb88b86fedcc9be50c2205d2018e975 100644
--- a/arch/arm64/boot/dts/qcom/sdm845.dtsi
+++ b/arch/arm64/boot/dts/qcom/sdm845.dtsi
@@ -5396,11 +5396,11 @@ slimbam: dma-controller@17184000 {
 			compatible = "qcom,bam-v1.7.4", "qcom,bam-v1.7.0";
 			qcom,controlled-remotely;
 			reg = <0 0x17184000 0 0x2a000>;
-			num-channels = <31>;
+			num-channels = <23>;
 			interrupts = <GIC_SPI 164 IRQ_TYPE_LEVEL_HIGH>;
 			#dma-cells = <1>;
 			qcom,ee = <1>;
-			qcom,num-ees = <2>;
+			qcom,num-ees = <4>;
 			iommus = <&apps_smmu 0x1806 0x0>;
 		};
 

---
base-commit: 1aa50d938e88fcad1312467bd09be4037bfe68ff
change-id: 20250821-sdm845-slimbam-channels-7b30485172ee

Best regards,
-- 
Stephan Gerhold <stephan.gerhold@linaro.org>

Re: [PATCH] arm64: dts: qcom: sdm845: Fix slimbam num-channels/ees

Posted by Bjorn Andersson 1 month, 1 week ago

On Thu, 21 Aug 2025 10:15:09 +0200, Stephan Gerhold wrote:
> Reading the hardware registers of the &slimbam on RB3 reveals that the BAM
> supports only 23 pipes (channels) and supports 4 EEs instead of 2. This
> hasn't caused problems so far since nothing is using the extra channels,
> but attempting to use them would lead to crashes.
> 
> The bam_dma driver might warn in the future if the num-channels in the DT
> are wrong, so correct the properties in the DT to avoid future regressions.
> 
> [...]

Applied, thanks!

[1/1] arm64: dts: qcom: sdm845: Fix slimbam num-channels/ees
      commit: 316294bb6695a43a9181973ecd4e6fb3e576a9f7

Best regards,
-- 
Bjorn Andersson <andersson@kernel.org>

Re: [PATCH] arm64: dts: qcom: sdm845: Fix slimbam num-channels/ees

Posted by Dmitry Baryshkov 1 month, 1 week ago

On Thu, Aug 21, 2025 at 10:15:09AM +0200, Stephan Gerhold wrote:
> Reading the hardware registers of the &slimbam on RB3 reveals that the BAM
> supports only 23 pipes (channels) and supports 4 EEs instead of 2. This
> hasn't caused problems so far since nothing is using the extra channels,
> but attempting to use them would lead to crashes.
> 
> The bam_dma driver might warn in the future if the num-channels in the DT
> are wrong, so correct the properties in the DT to avoid future regressions.
> 
> Cc: stable@vger.kernel.org
> Fixes: 27ca1de07dc3 ("arm64: dts: qcom: sdm845: add slimbus nodes")
> Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
> ---
>  arch/arm64/boot/dts/qcom/sdm845.dtsi | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry