Re: [PATCH v2 8/8] drm/msm/dpu: move INTF tearing checks to dpu_encoder_phys_cmd_init

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

On 30/07/2023 22:52, Marijn Suijten wrote:
> On 2023-07-30 03:35:18, Dmitry Baryshkov wrote:
>> As the INTF is fixed at the encoder creation time, we can move the
>> check whether INTF supports tearchck to dpu_encoder_phys_cmd_init().
>> This function can return an error if INTF doesn't have required feature.
>> Performing this check in dpu_encoder_phys_cmd_tearcheck_config() is less
>> useful, as this function returns void.
>>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>> ---
>>   .../drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c  | 41 +++++++++++--------
>>   1 file changed, 25 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> index 012986cff38c..adbd559a5290 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> @@ -325,24 +325,21 @@ static void dpu_encoder_phys_cmd_tearcheck_config(
>>   	unsigned long vsync_hz;
>>   	struct dpu_kms *dpu_kms;
>>   
>> -	if (phys_enc->has_intf_te) {
>> -		if (!phys_enc->hw_intf ||
>> -		    !phys_enc->hw_intf->ops.enable_tearcheck) {
>> -			DPU_DEBUG_CMDENC(cmd_enc, "tearcheck not supported\n");
>> -			return;
>> -		}
>> -
>> -		DPU_DEBUG_CMDENC(cmd_enc, "");
>> -	} else {
>> -		if (!phys_enc->hw_pp ||
>> -		    !phys_enc->hw_pp->ops.enable_tearcheck) {
>> -			DPU_DEBUG_CMDENC(cmd_enc, "tearcheck not supported\n");
>> -			return;
>> -		}
>> -
>> -		DPU_DEBUG_CMDENC(cmd_enc, "pp %d\n", phys_enc->hw_pp->idx - PINGPONG_0);
>> +	/*
>> +	 * TODO: if/when resource allocation is refactored, move this to a
>> +	 * place where the driver can actually return an error.
>> +	 */
>> +	if (!phys_enc->has_intf_te &&
>> +	    (!phys_enc->hw_pp ||
>> +	     !phys_enc->hw_pp->ops.enable_tearcheck)) {
> 
> We're probably overdoing it here if I request a WARN_ON when has_intf_te
> is true while enable_tearcheck is also non-NULL?
> 
>> +		DPU_DEBUG_CMDENC(cmd_enc, "tearcheck not supported\n");
>> +		return;
>>   	}
>>   
>> +	DPU_DEBUG_CMDENC(cmd_enc, "intf %d pp %d\n",
>> +			 phys_enc->hw_intf->idx - INTF_0,
>> +			 phys_enc->hw_pp->idx - PINGPONG_0);
> 
> Note that hw_pp wasn't printed when has_intf_te is true.  And it doesn't
> seem like that pointer is dereferenced anywhere in that case, perhaps
> hw_pp may even be NULL within dpu_encoder_phys_cmd_tearcheck_config() at
> some point.

No, if I understand correctly. It is only called from 
_dpu_encoder_phys_cmd_pingpong_config(), which checks for hw_pp. One can 
not run CMD mode display without a pingpong block anyway.

> 
>> +
>>   	mode = &phys_enc->cached_mode;
>>   
>>   	dpu_kms = phys_enc->dpu_kms;
>> @@ -768,10 +765,22 @@ struct dpu_encoder_phys *dpu_encoder_phys_cmd_init(
>>   	phys_enc->intf_mode = INTF_MODE_CMD;
>>   	cmd_enc->stream_sel = 0;
>>   
>> +	if (!phys_enc->hw_intf) {
>> +		DPU_ERROR_CMDENC(cmd_enc, "no INTF provided\n");
>> +
> 
> No need for this newline?

I just usually insert an empty line before return. Let's remove it.

> 
>> +		return ERR_PTR(-EINVAL);
>> +	}
>> +
>>   	/* DPU before 5.0 use PINGPONG for TE handling */
>>   	if (phys_enc->dpu_kms->catalog->mdss_ver->core_major_ver >= 5)
>>   		phys_enc->has_intf_te = true;
>>   
>> +	if (phys_enc->has_intf_te && !phys_enc->hw_intf->ops.enable_tearcheck) {
>> +		DPU_ERROR_CMDENC(cmd_enc, "tearcheck not supported\n");
>> +
> 
> Same here?
> 
> - Marijn
> 
>> +		return ERR_PTR(-EINVAL);
>> +	}
>> +
>>   	atomic_set(&cmd_enc->pending_vblank_cnt, 0);
>>   	init_waitqueue_head(&cmd_enc->pending_vblank_wq);
>>   
>> -- 
>> 2.39.2
>>

-- 
With best wishes
Dmitry