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

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 04/11/2022 16:58, Konrad Dybcio wrote:
> 
> 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.

I do not want to overcomplicate this. Let's make it dynamic once there 
is need for that. For now I expect this will be static.

> 
> 
> 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);
>>   }

-- 
With best wishes
Dmitry