Re: [PATCH 2/4] arm64: dts: qcom: sc7280: Add dma-coherent property into venus node

[Deepa Guthyappa Madivalara <deepa.madivalara@oss.qualcomm.com>]

On 8/1/2026 12:37 AM, Vishnu Reddy wrote:
> While testing with some higher resolution clips, the venus hardware
> triggers a fault due to wrong input data being received. Corruption
> was also observed in the captured output when the client dumped it
> to a file.
>
> On debugging, this was traced to the venus node not declaring
> dma-coherent. As a result, DMA buffers shared between the CPU and the
> venus video hardware/controller are not guaranteed to be I/O coherent:
> CPU writes to an input buffer can remain in CPU caches without being
> visible to the video hardware when it reads the same buffer, so the
> hardware receives input data that does not match what the CPU wrote.
> Likewise, on the capture path, data written by the video hardware to
> the output buffer may not be visible to the CPU, so the client reads
> stale or partial data, resulting in corruption.
>
> Add the dma-coherent property to the venus node so that DMA buffers
> shared between the CPU and the video hardware and controller remain
> coherent.
>
> Fixes: 37613aee2179 ("arm64: dts: qcom: sc7280: Add venus DT node")
> Cc: stable@vger.kernel.org
> Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
> ---
>   arch/arm64/boot/dts/qcom/kodiak.dtsi | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/qcom/kodiak.dtsi b/arch/arm64/boot/dts/qcom/kodiak.dtsi
> index f74fa66f1a67..98184760b4bf 100644
> --- a/arch/arm64/boot/dts/qcom/kodiak.dtsi
> +++ b/arch/arm64/boot/dts/qcom/kodiak.dtsi
> @@ -5024,6 +5024,8 @@ venus: video-codec@aa00000 {
>   					<&mmss_noc MASTER_VIDEO_P0 0 &mc_virt SLAVE_EBI1 0>;
>   			interconnect-names = "cpu-cfg", "video-mem";
>   
> +			dma-coherent;
> +
>   			iommus = <&apps_smmu 0x2180 0x20>;
>   			memory-region = <&video_mem>;

> Is this fix applicable to only Kodiak platform?
> Or are there other smmu coherent platforms that might need a similar fix?
>