Re: [PATCH v13 10/12] drm/msm/dpu: support SSPP assignment for quad-pipe case

[Dmitry Baryshkov]

On 31/07/2025 18:37, Jun Nie wrote:
Dmitry Baryshkov <dmitry.barysh...@oss.qualcomm.com> 于2025年7月31日周四 22:22写道：

On 31/07/2025 13:52, Jun Nie wrote:
Dmitry Baryshkov <dmitry.barysh...@oss.qualcomm.com> 于2025年7月31日周四 02:52写道：

On Mon, Jul 28, 2025 at 09:14:34PM +0800, 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....@linaro.org>
---
   drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 160 
++++++++++++++++++------------
   1 file changed, 99 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c 
b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
index 
55429f29a4b95594771d930efe42aaa4126f6f07..e1e16a8d5ac55ba52a0f460d62901dced65e3a9e
 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
@@ -959,6 +959,30 @@ static int dpu_plane_is_multirect_parallel_capable(struct 
dpu_hw_sspp *sspp,
   }


+static bool dpu_plane_get_single_pipe_in_stage(struct dpu_plane_state *pstate,
+                                            struct dpu_sw_pipe **single_pipe,
+                                            struct dpu_sw_pipe_cfg 
**single_pipe_cfg,
+                                            int stage_index)
+{
+     int pipe_idx, i, valid_pipe = 0;
+
+     for (i = 0; i < PIPES_PER_STAGE; i++) {

Why do you need to loop here? Is there a case when pipe 0 is not
assigned, but pipe 1 is?

Loop the pipe in a stage to count the valid pipes. If there are 2 valid
pipes in stage of the current plane, this function will return false.
Or you prefer the below coding?

1029         pipe_idx = stage_index * PIPES_PER_STAGE;
1030         if (drm_rect_width(&pstate->pipe_cfg[pipe_idx].src_rect) != 0 &&
1031             drm_rect_width(&pstate->pipe_cfg[pipe_idx +
1].src_rect) == 0) {

Yes, this is better from my POV. But the bigger question is why do you
need it at all? What is wrong with the existing check? Can it be that
pipe0 is not used, but pipe1 is used?

There is no case that pipe0 is not used, but pipe1 is used. Existing check
does not filter the plane which contains single pipe in a stage, which can
be a candidate for SSPP sharing. If the stage contains 2 valid pipes or
no valid pipes, it is skipped in dpu_plane_try_multirect_shared(), or it is
skipped to be stored in prev_adjacent_plane_state[].

Oh, I see, you need to check both pipes because you might need to skip 
it completely. I'd really prefer to have more explicit code:

- check for pipe0, skip this part of the plane if there is none
- check for pipe1, if there is none, it's a candidate for sharing.

If that becomes too ugly, then yes, explicit check for pipe0 and pipe1 
are better than a loop.



1032                         if (single_pipe)

You don't need these ifs. You always pass a valid pointer.

OK, a valid pointer can be passed though the return value may not be needed.

You are always passing a valid pointer there. If at any point we add 
other usage, then we'd need to add this if.


1033                                 *single_pipe = &pstate->pipe[pipe_idx];
1034                         if (single_pipe_cfg)
1035                                 *single_pipe_cfg =
&pstate->pipe_cfg[pipe_idx];
1036                 return true;
1037         }
1038
1039         return false;


+             pipe_idx = stage_index * PIPES_PER_STAGE + i;
+             if (drm_rect_width(&pstate->pipe_cfg[pipe_idx].src_rect) != 0) {
+                     valid_pipe++;
+                     if (valid_pipe > 1)
+                             return false;
+
+                     if (single_pipe)
+                             *single_pipe = &pstate->pipe[pipe_idx];
+                     if (single_pipe_cfg)
+                             *single_pipe_cfg = &pstate->pipe_cfg[pipe_idx];
+             }
+     }
+
+     return valid_pipe == 1;
+}
+
   static int dpu_plane_atomic_check_sspp(struct drm_plane *plane,
                                       struct drm_atomic_state *state,
                                       const struct drm_crtc_state *crtc_state)
@@ -1023,17 +1047,20 @@ static bool dpu_plane_try_multirect_parallel(struct 
dpu_sw_pipe *pipe, struct dp
   static int dpu_plane_try_multirect_shared(struct dpu_plane_state *pstate,
                                          struct dpu_plane_state 
*prev_adjacent_pstate,
                                          const struct msm_format *fmt,
-                                       uint32_t max_linewidth)
+                                       uint32_t max_linewidth, int stage_index)
   {
-     struct dpu_sw_pipe *pipe = &pstate->pipe[0];
-     struct dpu_sw_pipe *r_pipe = &pstate->pipe[1];
-     struct dpu_sw_pipe_cfg *pipe_cfg = &pstate->pipe_cfg[0];
-     struct dpu_sw_pipe *prev_pipe = &prev_adjacent_pstate->pipe[0];
-     struct dpu_sw_pipe_cfg *prev_pipe_cfg = 
&prev_adjacent_pstate->pipe_cfg[0];
+     struct dpu_sw_pipe *pipe, *prev_pipe;
+     struct dpu_sw_pipe_cfg *pipe_cfg, *prev_pipe_cfg;
        const struct msm_format *prev_fmt = 
msm_framebuffer_format(prev_adjacent_pstate->base.fb);
        u16 max_tile_height = 1;

-     if (prev_adjacent_pstate->pipe[1].sspp != NULL ||
+     if (!dpu_plane_get_single_pipe_in_stage(pstate, &pipe,
+                                             &pipe_cfg, stage_index))
+             return false;
+
+     if (!dpu_plane_get_single_pipe_in_stage(prev_adjacent_pstate,
+                                             &prev_pipe, &prev_pipe_cfg,
+                                             stage_index) ||
            prev_pipe->multirect_mode != DPU_SSPP_MULTIRECT_NONE)
                return false;

@@ -1048,11 +1075,6 @@ static int dpu_plane_try_multirect_shared(struct 
dpu_plane_state *pstate,
        if (MSM_FORMAT_IS_UBWC(prev_fmt))
                max_tile_height = max(max_tile_height, prev_fmt->tile_height);

-     r_pipe->multirect_index = DPU_SSPP_RECT_SOLO;
-     r_pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
-
-     r_pipe->sspp = NULL;
-
        if (dpu_plane_is_parallel_capable(pipe_cfg, fmt, max_linewidth) &&
            dpu_plane_is_parallel_capable(prev_pipe_cfg, prev_fmt, max_linewidth) 
&&
            (pipe_cfg->dst_rect.x1 >= prev_pipe_cfg->dst_rect.x2 ||
@@ -1181,36 +1203,69 @@ static int dpu_plane_virtual_atomic_check(struct 
drm_plane *plane,
        return 0;
   }

+static int dpu_plane_assign_resource_in_stage(struct dpu_sw_pipe *pipe,
+                                           struct dpu_sw_pipe_cfg *pipe_cfg,
+                                           struct drm_plane_state *plane_state,
+                                           struct dpu_global_state 
*global_state,
+                                           struct drm_crtc *crtc,
+                                           struct dpu_rm_sspp_requirements 
*reqs)
+{
+     struct drm_plane *plane = plane_state->plane;
+     struct dpu_kms *dpu_kms = _dpu_plane_get_kms(plane);
+     struct dpu_sw_pipe *r_pipe = pipe + 1;
+     struct dpu_sw_pipe_cfg *r_pipe_cfg = pipe_cfg + 1;
+
+     if (drm_rect_width(&pipe_cfg->src_rect) != 0) {
+             pipe->sspp = dpu_rm_reserve_sspp(&dpu_kms->rm, global_state, 
crtc, reqs);
+             if (!pipe->sspp)
+                     return -ENODEV;
+             pipe->multirect_index = DPU_SSPP_RECT_SOLO;
+             pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
+     }
+
+     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))
+             goto stage_assinged;
+
+     if (drm_rect_width(&r_pipe_cfg->src_rect) != 0) {
+             r_pipe->sspp = dpu_rm_reserve_sspp(&dpu_kms->rm, global_state, 
crtc, reqs);
+             if (!r_pipe->sspp)
+                     return -ENODEV;
+             r_pipe->multirect_index = DPU_SSPP_RECT_SOLO;
+             r_pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
+     }
+
+stage_assinged:
+     return 0;
+}
+
   static int dpu_plane_virtual_assign_resources(struct drm_crtc *crtc,
                                              struct dpu_global_state 
*global_state,
                                              struct drm_atomic_state *state,
                                              struct drm_plane_state 
*plane_state,
-                                           struct drm_plane_state 
*prev_adjacent_plane_state)
+                                           struct drm_plane_state 
**prev_adjacent_plane_state)
   {
        const struct drm_crtc_state *crtc_state = NULL;
        struct drm_plane *plane = plane_state->plane;
        struct dpu_kms *dpu_kms = _dpu_plane_get_kms(plane);
        struct dpu_rm_sspp_requirements reqs;
-     struct dpu_plane_state *pstate, *prev_adjacent_pstate;
+     struct dpu_plane_state *pstate, *prev_adjacent_pstate[STAGES_PER_PLANE];
        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;
        const struct msm_format *fmt;
-     int i;
+     int i, ret;

        if (plane_state->crtc)
                crtc_state = drm_atomic_get_new_crtc_state(state,
                                                           plane_state->crtc);

        pstate = to_dpu_plane_state(plane_state);
-     prev_adjacent_pstate = prev_adjacent_plane_state ?
-             to_dpu_plane_state(prev_adjacent_plane_state) : NULL;
-
-     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 < STAGES_PER_PLANE; i++)
+             prev_adjacent_pstate[i] = prev_adjacent_plane_state[i] ?
+                     to_dpu_plane_state(prev_adjacent_plane_state[i]) : NULL;

        for (i = 0; i < PIPES_PER_PLANE; i++)
                pstate->pipe[i].sspp = NULL;
@@ -1225,42 +1280,27 @@ static int dpu_plane_virtual_assign_resources(struct 
drm_crtc *crtc,

        reqs.rot90 = drm_rotation_90_or_270(plane_state->rotation);

-     if (drm_rect_width(&r_pipe_cfg->src_rect) == 0) {
-             if (!prev_adjacent_pstate ||
-                 !dpu_plane_try_multirect_shared(pstate, prev_adjacent_pstate, 
fmt,
-                                                 
dpu_kms->catalog->caps->max_linewidth)) {
-                     pipe->sspp = dpu_rm_reserve_sspp(&dpu_kms->rm, global_state, 
crtc, &reqs);
-                     if (!pipe->sspp)
-                             return -ENODEV;
-
-                     r_pipe->sspp = NULL;
+     for (i = 0; i < STAGES_PER_PLANE; i++) {
+             if (!prev_adjacent_pstate[i])
+                     goto assignment;

-                     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;
-             }
-     } else {
-             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;
+             if (dpu_plane_try_multirect_shared(pstate, 
prev_adjacent_pstate[i], fmt,
+                                                
dpu_kms->catalog->caps->max_linewidth,
+                                                i))
+                     continue;


if (prev_adjacent_pstate[i] &&
      dpu_plane_try_multirect_shared())
          continue;

No need for the goto.

Right, it will be simpler.


-                     pipe->multirect_index = DPU_SSPP_RECT_SOLO;
-                     pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
+assignment:
+             if (dpu_plane_get_single_pipe_in_stage(pstate, NULL, NULL, i))
+                     prev_adjacent_plane_state[i] = plane_state;

-                     r_pipe->multirect_index = DPU_SSPP_RECT_SOLO;
-                     r_pipe->multirect_mode = DPU_SSPP_MULTIRECT_NONE;
-             }
+             pipe = &pstate->pipe[i * PIPES_PER_STAGE];
+             pipe_cfg = &pstate->pipe_cfg[i * PIPES_PER_STAGE];
+             ret = dpu_plane_assign_resource_in_stage(pipe, pipe_cfg,
+                                                      plane_state,
+                                                      global_state,
+                                                      crtc, &reqs);
+             if (ret)
+                     return ret;
        }

        return dpu_plane_atomic_check_sspp(plane, state, crtc_state);
@@ -1273,7 +1313,7 @@ int dpu_assign_plane_resources(struct dpu_global_state 
*global_state,
                               unsigned int num_planes)
   {
        unsigned int i;
-     struct drm_plane_state *prev_adjacent_plane_state = NULL;
+     struct drm_plane_state *prev_adjacent_plane_state[STAGES_PER_PLANE] = { 
NULL };

        for (i = 0; i < num_planes; i++) {
                struct drm_plane_state *plane_state = states[i];
@@ -1284,11 +1324,9 @@ int dpu_assign_plane_resources(struct dpu_global_state 
*global_state,

                int ret = dpu_plane_virtual_assign_resources(crtc, global_state,
                                                             state, plane_state,
-                                                          
prev_adjacent_plane_state);
+                                                          
&prev_adjacent_plane_state[0]);

It's exactly the prev_adjacent_plane_state.

Yes, I will change it.


                if (ret)
                        break;
-
-             prev_adjacent_plane_state = plane_state;
        }

        return 0;

--
2.34.1


--
With best wishes
Dmitry


--
With best wishes
Dmitry


--
With best wishes
Dmitry