linux-kernel - Re: [PATCH 6/7] drm/msm/dpu: allocate single CTL for DPU >= 5.0

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Message-ID: <4aix26abutkas2fpj6ubu2hbqeljpgr5e3m24akeb3jz33limj@c7rymwz6zmft>
Date: Fri, 21 Feb 2025 00:34:12 +0100
From: Marijn Suijten <marijn.suijten@...ainline.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Rob Clark <robdclark@...il.com>, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/7] drm/msm/dpu: allocate single CTL for DPU >= 5.0

On 2025-02-20 12:26:23, Dmitry Baryshkov wrote:
> Unlike previous generation, since DPU 5.0 it is possible to use just one
> CTL to handle all INTF and WB blocks for a single output. And one has to
> use single CTL to support bonded DSI config. Allocate single CTL for
> these DPU versions.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 17 +++++++++++++----
>  drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h |  2 ++
>  2 files changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> index 5baf9df702b84b74ba00e703ad3cc12afb0e94a4..4dbc9bc7eb4f151f83055220665ee5fd238ae7ba 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> @@ -53,6 +53,8 @@ int dpu_rm_init(struct drm_device *dev,
>  	/* Clear, setup lists */
>  	memset(rm, 0, sizeof(*rm));
>  
> +	rm->has_legacy_ctls = (cat->mdss_ver->core_major_ver < 5);
> +
>  	/* Interrogate HW catalog and create tracking items for hw blocks */
>  	for (i = 0; i < cat->mixer_count; i++) {
>  		struct dpu_hw_mixer *hw;
> @@ -381,10 +383,16 @@ static int _dpu_rm_reserve_ctls(
>  	int i = 0, j, num_ctls;
>  	bool needs_split_display;
>  
> -	/* each hw_intf needs its own hw_ctrl to program its control path */
> -	num_ctls = top->num_intf;
> +	if (rm->has_legacy_ctls) {
> +		/* each hw_intf needs its own hw_ctrl to program its control path */
> +		num_ctls = top->num_intf;
>  
> -	needs_split_display = _dpu_rm_needs_split_display(top);
> +		needs_split_display = _dpu_rm_needs_split_display(top);
> +	} else {
> +		/* use single CTL */
> +		num_ctls = 1;
> +		needs_split_display = false;
> +	}
>  
>  	for (j = 0; j < ARRAY_SIZE(rm->ctl_blks); j++) {
>  		const struct dpu_hw_ctl *ctl;
> @@ -402,7 +410,8 @@ static int _dpu_rm_reserve_ctls(
>  
>  		DPU_DEBUG("ctl %d caps 0x%lX\n", j + CTL_0, features);
>  
> -		if (needs_split_display != has_split_display)
> +		if (rm->has_legacy_ctls &&
> +		    needs_split_display != has_split_display)

I deduced a long time ago that the check for rm->has_legacy_ctls is not needed.

needs_split_display is always false on DPU >= 5, and neither of those SoCs has
DPU_CTRL_SPLIT_DISPLAY which means false != false is false, and this condition
never triggers on active CTLs even without checking has_legacy_ctls.

Other than that, this is all successfully tested and:

Reviewed-by: Marijn Suijten <marijn.suijten@...ainline.org>

>  			continue;
>  
>  		ctl_idx[i] = j;
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
> index 99bd594ee0d1995eca5a1f661b15e24fdf6acf39..130f753c36338544e84a305b266c3b47fa028d84 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
> @@ -24,6 +24,7 @@ struct dpu_global_state;
>   * @dspp_blks: array of dspp hardware resources
>   * @hw_sspp: array of sspp hardware resources
>   * @cdm_blk: cdm hardware resource
> + * @has_legacy_ctls: DPU uses pre-ACTIVE CTL blocks.
>   */
>  struct dpu_rm {
>  	struct dpu_hw_blk *pingpong_blks[PINGPONG_MAX - PINGPONG_0];
> @@ -37,6 +38,7 @@ struct dpu_rm {
>  	struct dpu_hw_blk *dsc_blks[DSC_MAX - DSC_0];
>  	struct dpu_hw_sspp *hw_sspp[SSPP_MAX - SSPP_NONE];
>  	struct dpu_hw_blk *cdm_blk;
> +	bool has_legacy_ctls;
>  };
>  
>  struct dpu_rm_sspp_requirements {
> 
> -- 
> 2.39.5
>