Re: [PATCH v3 6/8] drm/msm/dpu: add support for MDP_TOP blackhole

[Konrad Dybcio <konrad.dybcio@somainline.org>]

On 04/11/2022 14:03, Dmitry Baryshkov wrote:
> On sm8450 a register block was removed from MDP TOP. Accessing it during
> snapshotting results in NoC errors / immediate reboot. Skip accessing
> these registers during snapshot.

Must have been fun to debug..


>
> Tested-by: Vinod Koul <vkoul@kernel.org>
> Reviewed-by: Vinod Koul <vkoul@kernel.org>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h |  1 +
>   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c        | 11 +++++++++--
>   2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> index 38aa38ab1568..4730f8268f2a 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> @@ -92,6 +92,7 @@ enum {
>   	DPU_MDP_UBWC_1_0,
>   	DPU_MDP_UBWC_1_5,
>   	DPU_MDP_AUDIO_SELECT,
> +	DPU_MDP_PERIPH_0_REMOVED,
>   	DPU_MDP_MAX
>   };
>   
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index f3660cd14f4f..95d8765c1c53 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -927,8 +927,15 @@ static void dpu_kms_mdp_snapshot(struct msm_disp_state *disp_state, struct msm_k
>   		msm_disp_snapshot_add_block(disp_state, cat->wb[i].len,
>   				dpu_kms->mmio + cat->wb[i].base, "wb_%d", i);
>   
> -	msm_disp_snapshot_add_block(disp_state, cat->mdp[0].len,
> -			dpu_kms->mmio + cat->mdp[0].base, "top");
> +	if (dpu_kms->hw_mdp->caps->features & BIT(DPU_MDP_PERIPH_0_REMOVED)) {
> +		msm_disp_snapshot_add_block(disp_state, 0x380,
> +				dpu_kms->mmio + cat->mdp[0].base, "top");
> +		msm_disp_snapshot_add_block(disp_state, cat->mdp[0].len - 0x3a8,
> +				dpu_kms->mmio + cat->mdp[0].base + 0x3a8, "top_2");

Are these values expected to stay the same on different new-gen SoCs? 
Maybe it would

be worth making it dynamic.


Konrad

> +	} else {
> +		msm_disp_snapshot_add_block(disp_state, cat->mdp[0].len,
> +				dpu_kms->mmio + cat->mdp[0].base, "top");
> +	}
>   
>   	pm_runtime_put_sync(&dpu_kms->pdev->dev);
>   }