drm/amd/display: Fix warnings on S3 resume

This is a followup to the following revert:

Rex Zhu    Revert "drm/amd/display: Match actual state during S3
           resume."

Three things needed to be addressed:

1. Potential memory leak on dc_state creation in atomic_check during
   s3 resume
2. Warnings are now seen in dmesg during S3 resume
3. Since dc_state is now created in atomic_check, what the reverted
   patch was addressing needs to be reevaluated.

This change addresses the above:

1. Since the suspend procedure calls drm_atomic_state_clear, our hook
   for releasing the dc_state is called. This frees it before
   atomic_check creates it during resume. The leak does not occur.

2. The dc_crtc/plane_state references kept by the atomic states need to
   be released before calling atomic_check, which warns if they are
   non-null. This is because atomic_check is responsible for creating
   the dc_*_states. This is a special case for S3 resume, since the
   atomic state duplication that occurs during suspend also copies a
   reference to the dc_*_states.

3. See 2. comments are also updated to reflect this.

Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index cd19db28a845d87a2cddfdeb08c7143516cabd05..889ed24084e866bb846d9b6cc1f52a38e51cb5eb 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -643,6 +643,11 @@ int amdgpu_dm_display_resume(struct amdgpu_device *adev)
        struct drm_connector *connector;
        struct drm_crtc *crtc;
        struct drm_crtc_state *new_crtc_state;
+       struct dm_crtc_state *dm_new_crtc_state;
+       struct drm_plane *plane;
+       struct drm_plane_state *new_plane_state;
+       struct dm_plane_state *dm_new_plane_state;
+
        int ret = 0;
        int i;
 
@@ -681,6 +686,29 @@ int amdgpu_dm_display_resume(struct amdgpu_device *adev)
        for_each_new_crtc_in_state(adev->dm.cached_state, crtc, new_crtc_state, i)
                new_crtc_state->active_changed = true;
 
+       /*
+        * atomic_check is expected to create the dc states. We need to release
+        * them here, since they were duplicated as part of the suspend
+        * procedure.
+        */
+       for_each_new_crtc_in_state(adev->dm.cached_state, crtc, new_crtc_state, i) {
+               dm_new_crtc_state = to_dm_crtc_state(new_crtc_state);
+               if (dm_new_crtc_state->stream) {
+                       WARN_ON(kref_read(&dm_new_crtc_state->stream->refcount) > 1);
+                       dc_stream_release(dm_new_crtc_state->stream);
+                       dm_new_crtc_state->stream = NULL;
+               }
+       }
+
+       for_each_new_plane_in_state(adev->dm.cached_state, plane, new_plane_state, i) {
+               dm_new_plane_state = to_dm_plane_state(new_plane_state);
+               if (dm_new_plane_state->dc_state) {
+                       WARN_ON(kref_read(&dm_new_plane_state->dc_state->refcount) > 1);
+                       dc_plane_state_release(dm_new_plane_state->dc_state);
+                       dm_new_plane_state->dc_state = NULL;
+               }
+       }
+
        ret = drm_atomic_helper_resume(ddev, adev->dm.cached_state);
 
        drm_atomic_state_put(adev->dm.cached_state);