Re: [PATCH] Revert "arm64: dts: qcom: sdm845: Affirm IDR0.CCTW on apps_smmu"

[Dmitry Baryshkov]

On Tue, Feb 25, 2025 at 02:44:40PM +0100, Konrad Dybcio wrote:
> From: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
> 
> There are reports that the pagetable walker cache coherency is not a
> given across the spectrum of SDM845/850 devices, leading to lock-ups
> and resets. It works fine on some devices (like the Dragonboard 845c,
> but not so much on the Lenovo Yoga C630).
> 
> This unfortunately looks like a fluke in firmware development, where
> likely somewhere in the vast hypervisor stack, a change to accommodate
> for this was only introduced after the initial software release (which
> often serves as a baseline for products).
> 
> Revert the change to avoid additional guesswork around crashes.
> 
> This reverts commit 6b31a9744b8726c69bb0af290f8475a368a4b805.
> 
> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-arm-msm/20250215-yoga-dma-coherent-v1-1-2419ee184a81@xxxxxxxxxx/
> Fixes: 6b31a9744b87 ("arm64: dts: qcom: sdm845: Affirm IDR0.CCTW on apps_smmu")
> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
> ---
>  arch/arm64/boot/dts/qcom/sdm845.dtsi | 1 -
>  1 file changed, 1 deletion(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>

Should we enable dma-coherent for RB3 only then?


-- 
With best wishes
Dmitry