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

[Marijn Suijten <marijn.suijten@somainline.org>]

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.

> +
>  	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?

> +		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
>