linux-kernel - Re: [PATCH v6 12/15] drm/msm/dpu: blend pipes per mixer pairs config

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Message-ID: <qrwo5jtdj64vu27jn3v2wwyuxu25bjqrybj5jjfc5ifiotgzit@6vx2km46j7b3>
Date: Mon, 17 Feb 2025 21:57:23 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Jun Nie <jun.nie@...aro.org>
Cc: Rob Clark <robdclark@...il.com>, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 12/15] drm/msm/dpu: blend pipes per mixer pairs config

On Mon, Feb 17, 2025 at 10:16:01PM +0800, Jun Nie wrote:
> Currently, only 2 pipes are used at most for a plane. A stage structure
> describes the configuration for a mixer pair. So only one stage is needed
> for current usage cases. The quad-pipe case will be added in future and 2
> stages are used in the case. So extend the stage to an array with array size
> STAGES_PER_PLANE and blend pipes per mixer pair with configuration in the
> stage structure.
> 
> Signed-off-by: Jun Nie <jun.nie@...aro.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    | 45 +++++++++++++++++++----------
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h |  1 +
>  2 files changed, 30 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> index 81474823e6799132db71c9712046d359e3535d90..50acaf25a3ffcc94354faaa816fe74566784844c 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> @@ -401,7 +401,7 @@ static void _dpu_crtc_blend_setup_pipe(struct drm_crtc *crtc,
>  				       struct dpu_hw_stage_cfg *stage_cfg
>  				      )
>  {
> -	uint32_t lm_idx;
> +	uint32_t lm_idx, lm_in_pair;
>  	enum dpu_sspp sspp_idx;
>  	struct drm_plane_state *state;
>  
> @@ -426,7 +426,8 @@ static void _dpu_crtc_blend_setup_pipe(struct drm_crtc *crtc,
>  	stage_cfg->multirect_index[stage][stage_idx] = pipe->multirect_index;
>  
>  	/* blend config update */
> -	for (lm_idx = 0; lm_idx < num_mixers; lm_idx++)
> +	lm_in_pair = num_mixers > 1 ? 2 : 1;
> +	for (lm_idx = 0; lm_idx < lm_in_pair; lm_idx++)
>  		mixer[lm_idx].lm_ctl->ops.update_pending_flush_sspp(mixer[lm_idx].lm_ctl, sspp_idx);

I almost missed this. Why is this necessary?

>  }
>  

[...]

> @@ -535,8 +543,13 @@ static void _dpu_crtc_blend_setup(struct drm_crtc *crtc)
>  			mixer[i].mixer_op_mode,
>  			ctl->idx - CTL_0);
>  
> +		/*
> +		 * call dpu_hw_ctl_setup_blendstage() to blend layers per stage cfg.
> +		 * There are 4 mixers at most. The first 2 are for the left half, and
> +		 * the later 2 are for the right half.
> +		 */

The comment is invalid until you introduce quad pipe, currently there
are 2 mixers at most. However you can just say something like 'stage
data is shared between PIPES_PER_STAGE pipes'.

>  		ctl->ops.setup_blendstage(ctl, mixer[i].hw_lm->idx,
> -			&stage_cfg);
> +			&stage_cfg[i / PIPES_PER_STAGE]);
>  	}
>  }
>  
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
> index 5f010d36672cc6440c69779908b315aab285eaf0..64e220987be5682f26d02074505c5474a547a814 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
> @@ -34,6 +34,7 @@
>  #define DPU_MAX_PLANES			4
>  #endif
>  
> +#define STAGES_PER_PLANE		2
>  #define PIPES_PER_PLANE			2
>  #define PIPES_PER_STAGE			2
>  #ifndef DPU_MAX_DE_CURVES
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry