Re: [PATCH v7 13/15] drm/msm/dpu: support SSPP assignment for quad-pipe case

[Jessica Zhang <quic_jesszhan@quicinc.com>]

On 2/26/2025 4:31 AM, Jun Nie wrote:
> Currently, SSPPs are assigned to a maximum of two pipes. However,
> quad-pipe usage scenarios require four pipes and involve configuring
> two stages. In quad-pipe case, the first two pipes share a set of
> mixer configurations and enable multi-rect mode when certain
> conditions are met. The same applies to the subsequent two pipes.
> 
> Assign SSPPs to the pipes in each stage using a unified method and
> to loop the stages accordingly.
> 
> Signed-off-by: Jun Nie <jun.nie@linaro.org>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c  | 11 +++++
>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h  |  2 +
>   drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 71 ++++++++++++++++++++-----------
>   3 files changed, 58 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> index 0a053c5888262d863a1e549e14e3aa40a80c3f06..9405453cbf5d852e72a5f954cd8c6aed3a222723 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> @@ -1366,6 +1366,17 @@ int dpu_crtc_vblank(struct drm_crtc *crtc, bool en)
>   	return 0;
>   }
>   
> +/**
> + * dpu_crtc_get_num_lm - Get mixer number in this CRTC pipeline
> + * @state: Pointer to drm crtc state object
> + */
> +unsigned int dpu_crtc_get_num_lm(const struct drm_crtc_state *state)
> +{
> +	struct dpu_crtc_state *cstate = to_dpu_crtc_state(state);
> +
> +	return cstate->num_mixers;
> +}
> +
>   #ifdef CONFIG_DEBUG_FS
>   static int _dpu_debugfs_status_show(struct seq_file *s, void *data)
>   {
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> index 0b148f3ce0d7af80ec4ffcd31d8632a5815b16f1..b14bab2754635953da402d09e11a43b9b4cf4153 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> @@ -264,4 +264,6 @@ static inline enum dpu_crtc_client_type dpu_crtc_get_client_type(
>   
>   void dpu_crtc_frame_event_cb(struct drm_crtc *crtc, u32 event);
>   
> +unsigned int dpu_crtc_get_num_lm(const struct drm_crtc_state *state);
> +
>   #endif /* _DPU_CRTC_H_ */
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> index d67f2ad20b4754ca4bcb759a65a39628b7236b0f..d1d6c91ed0f8e1c62b757ca42546fbc421609f72 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> @@ -1112,11 +1112,10 @@ static int dpu_plane_virtual_assign_resources(struct drm_crtc *crtc,
>   	struct dpu_rm_sspp_requirements reqs;
>   	struct dpu_plane_state *pstate;
>   	struct dpu_sw_pipe *pipe;
> -	struct dpu_sw_pipe *r_pipe;
>   	struct dpu_sw_pipe_cfg *pipe_cfg;
> -	struct dpu_sw_pipe_cfg *r_pipe_cfg;
> +	struct dpu_plane *pdpu = to_dpu_plane(plane);
>   	const struct msm_format *fmt;
> -	int i;
> +	int i, num_lm, stage_id, num_stages;
>   
>   	if (plane_state->crtc)
>   		crtc_state = drm_atomic_get_new_crtc_state(state,
> @@ -1124,11 +1123,6 @@ static int dpu_plane_virtual_assign_resources(struct drm_crtc *crtc,
>   
>   	pstate = to_dpu_plane_state(plane_state);
>   
> -	pipe = &pstate->pipe[0];
> -	r_pipe = &pstate->pipe[1];
> -	pipe_cfg = &pstate->pipe_cfg[0];
> -	r_pipe_cfg = &pstate->pipe_cfg[1];
> -
>   	for (i = 0; i < PIPES_PER_PLANE; i++)
>   		pstate->pipe[i].sspp = NULL;
>   
> @@ -1142,24 +1136,49 @@ static int dpu_plane_virtual_assign_resources(struct drm_crtc *crtc,
>   
>   	reqs.rot90 = drm_rotation_90_or_270(plane_state->rotation);
>   
> -	pipe->sspp = dpu_rm_reserve_sspp(&dpu_kms->rm, global_state, crtc, &reqs);
> -	if (!pipe->sspp)
> -		return -ENODEV;
> -
> -	if (!dpu_plane_try_multirect_parallel(pipe, pipe_cfg, r_pipe, r_pipe_cfg,
> -					      pipe->sspp,
> -					      msm_framebuffer_format(plane_state->fb),
> -					      dpu_kms->catalog->caps->max_linewidth)) {
> -		/* multirect is not possible, use two SSPP blocks */
> -		r_pipe->sspp = dpu_rm_reserve_sspp(&dpu_kms->rm, global_state, crtc, &reqs);
> -		if (!r_pipe->sspp)
> -			return -ENODEV;
> -
> -		pipe->multirect_index = DPU_SSPP_RECT_SOLO;
> -		pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
> -
> -		r_pipe->multirect_index = DPU_SSPP_RECT_SOLO;
> -		r_pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
> +	num_lm = dpu_crtc_get_num_lm(crtc_state);

Hi Jun,

Just wondering, why not use dpu_rm_get_assigned_resources() here instead 
of adding a new *_get_num_lm() API?

Thanks,

Jessica Zhang

> +	num_stages = (num_lm + 1) / 2;
> +	for (stage_id = 0; stage_id < num_stages; stage_id++) {
> +		for (i = stage_id * PIPES_PER_STAGE; i < (stage_id + 1) * PIPES_PER_STAGE; i++) {
> +			struct dpu_sw_pipe *r_pipe;
> +			struct dpu_sw_pipe_cfg *r_pipe_cfg;
> +
> +			pipe = &pstate->pipe[i];
> +			pipe_cfg = &pstate->pipe_cfg[i];
> +
> +			if (drm_rect_width(&pipe_cfg->src_rect) == 0)
> +				break;
> +
> +			pipe->sspp = dpu_rm_reserve_sspp(&dpu_kms->rm, global_state, crtc, &reqs);
> +			if (!pipe->sspp)
> +				return -ENODEV;
> +
> +			/* use solo SSPP for the 2nd pipe in pipe pair */
> +			if (i % PIPES_PER_STAGE != 0)
> +				goto use_solo_sspp;
> +
> +			/*
> +			 * Check multi-rect opportunity for the 2nd pipe in the
> +			 * pair. SSPP multi-rect mode cross mixer pairs is not
> +			 * supported.
> +			 */
> +			r_pipe = &pstate->pipe[i + 1];
> +			r_pipe_cfg = &pstate->pipe_cfg[i + 1];
> +
> +			if (drm_rect_width(&r_pipe_cfg->src_rect) != 0 &&
> +			    dpu_plane_try_multirect_parallel(pipe, pipe_cfg, r_pipe, r_pipe_cfg,
> +							      pipe->sspp,
> +							      msm_framebuffer_format(plane_state->fb),
> +							      dpu_kms->catalog->caps->max_linewidth)) {
> +				i++;
> +				continue;
> +			}
> +use_solo_sspp:
> +			pipe->multirect_index = DPU_SSPP_RECT_SOLO;
> +			pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
> +			DPU_DEBUG_PLANE(pdpu, "allocating sspp_%d for pipe %d.\n",
> +					pipe->sspp->idx - SSPP_NONE, i);
> +		}
>   	}
>   
>   	return dpu_plane_atomic_check_sspp(plane, state, crtc_state);
> 
> -- 
> 2.34.1
>