compositor-drm: Allow scanout plane to be occluded by overlay

a0f8276fe814 ("compositor-drm: Disallow overlapping overlay planes") was
a little too pessimistic in rejecting occluded views. Whilst it
correctly prevented overlay planes from occluding each other, it also
prevented overlay planes from occluding the scanout plane.

This is undesirable: the primary/scanout plane is specified to stack
strictly below all overlay planes, so there is no need to reject a plane
from consideration for scanout due to being occluded by an overlay
plane.

Shift the check downwards so it only applies to overlay rather than
scanout planes.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

diff --git a/libweston/compositor-drm.c b/libweston/compositor-drm.c
index 3e70265..a99ac8e 100644 (file)
--- a/libweston/compositor-drm.c
+++ b/libweston/compositor-drm.c
@@ -3392,7 +3392,8 @@ drm_output_propose_state(struct weston_output *output_base,
                struct drm_plane_state *ps = NULL;
                bool force_renderer = false;
                pixman_region32_t clipped_view;
-               bool occluded = false;
+               bool totally_occluded = false;
+               bool overlay_occluded = false;
 
                /* If this view doesn't touch our output at all, there's no
                 * reason to do anything with it. */
@@ -3416,8 +3417,8 @@ drm_output_propose_state(struct weston_output *output_base,
                pixman_region32_init(&surface_overlap);
                pixman_region32_subtract(&surface_overlap, &clipped_view,
                                         &occluded_region);
-               occluded = !pixman_region32_not_empty(&surface_overlap);
-               if (occluded) {
+               totally_occluded = !pixman_region32_not_empty(&surface_overlap);
+               if (totally_occluded) {
                        pixman_region32_fini(&surface_overlap);
                        pixman_region32_fini(&clipped_view);
                        continue;
@@ -3439,13 +3440,13 @@ drm_output_propose_state(struct weston_output *output_base,
                pixman_region32_intersect(&surface_overlap, &occluded_region,
                                          &clipped_view);
                if (pixman_region32_not_empty(&surface_overlap))
-                       force_renderer = true;
+                       overlay_occluded = true;
                pixman_region32_fini(&surface_overlap);
 
                /* The cursor plane is 'special' in the sense that we can still
                 * place it in the legacy API, and we gate that with a separate
                 * cursors_are_broken flag. */
-               if (!force_renderer && !b->cursors_are_broken)
+               if (!force_renderer && !overlay_occluded && !b->cursors_are_broken)
                        ps = drm_output_prepare_cursor_view(state, ev);
 
                /* If sprites are disabled or the view is not fully opaque, we
@@ -3462,7 +3463,8 @@ drm_output_propose_state(struct weston_output *output_base,
                 * scanout plane. */
                if (!ps && !force_renderer && !renderer_ok)
                        ps = drm_output_prepare_scanout_view(state, ev, mode);
-               if (!ps && !force_renderer)
+
+               if (!ps && !overlay_occluded && !force_renderer)
                        ps = drm_output_prepare_overlay_view(state, ev, mode);
 
                if (ps) {