drm/amd/display: Do not elevate mem_type change to full update

[Why]

There should not be any need to revalidate bandwidth on memory placement
change, since the fb is expected to be pinned to DCN-accessable memory
before scanout. For APU it's DRAM, and DGPU, it's VRAM. However, async
flips + memory type change needs to be rejected.

[How]

Do not set lock_and_validation_needed on mem_type change. Instead,
reject an async_flip request if the crtc's buffer(s) changed mem_type.

This may fix stuttering/corruption experienced with PSR SU and PSR1
panels, if the compositor allocates fbs in both VRAM carveout and GTT
and flips between them.

Fixes: a7c0cad ("drm/amd/display: ensure async flips are only accepted for fast updates")
Reviewed-by: Tom Chung <[email protected]>
Signed-off-by: Leo Li <[email protected]>
Signed-off-by: Tom Chung <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: leo-sunli1

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -11464,6 +11464,25 @@ static int dm_crtc_get_cursor_mode(struct amdgpu_device *adev,
 	return 0;
 }
 
+static bool amdgpu_dm_crtc_mem_type_changed(struct drm_device *dev,
+					    struct drm_atomic_state *state,
+					    struct drm_crtc_state *crtc_state)
+{
+	struct drm_plane *plane;
+	struct drm_plane_state *new_plane_state, *old_plane_state;
+
+	drm_for_each_plane_mask(plane, dev, crtc_state->plane_mask) {
+		new_plane_state = drm_atomic_get_plane_state(state, plane);
+		old_plane_state = drm_atomic_get_plane_state(state, plane);
+
+		if (old_plane_state->fb && new_plane_state->fb &&
+		    get_mem_type(old_plane_state->fb) != get_mem_type(new_plane_state->fb))
+			return true;
+	}
+
+	return false;
+}
+
 /**
  * amdgpu_dm_atomic_check() - Atomic check implementation for AMDgpu DM.
  *
@@ -11661,10 +11680,6 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 
 	/* Remove exiting planes if they are modified */
 	for_each_oldnew_plane_in_descending_zpos(state, plane, old_plane_state, new_plane_state) {
-		if (old_plane_state->fb && new_plane_state->fb &&
-		    get_mem_type(old_plane_state->fb) !=
-		    get_mem_type(new_plane_state->fb))
-			lock_and_validation_needed = true;
 
 		ret = dm_update_plane_state(dc, state, plane,
 					    old_plane_state,
@@ -11959,9 +11974,11 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 
 		/*
 		 * Only allow async flips for fast updates that don't change
-		 * the FB pitch, the DCC state, rotation, etc.
+		 * the FB pitch, the DCC state, rotation, mem_type, etc.
 		 */
-		if (new_crtc_state->async_flip && lock_and_validation_needed) {
+		if (new_crtc_state->async_flip &&
+		    (lock_and_validation_needed ||
+		     amdgpu_dm_crtc_mem_type_changed(dev, state, new_crtc_state))) {
 			drm_dbg_atomic(crtc->dev,
 				       "[CRTC:%d:%s] async flips are only supported for fast updates\n",
 				       crtc->base.id, crtc->name);