[PATCH weston 37/68] compositor-drm: Don't repaint if no damage

[Daniel Stone]

If we don't have any damage for the primary plane, then don't force a
repaint; simply reuse the old buffer we already have.

Differential Revision: https://phabricator.freedesktop.org/D1499

Signed-off-by: Daniel Stone <daniels at collabora.com>
---
 libweston/compositor-drm.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/libweston/compositor-drm.c b/libweston/compositor-drm.c
index e575429..f0a13e1 100644
--- a/libweston/compositor-drm.c
+++ b/libweston/compositor-drm.c
@@ -1430,6 +1430,7 @@ drm_output_render(struct drm_output *output, pixman_region32_t *damage)
 {
 	struct weston_compositor *c = output->base.compositor;
 	struct drm_plane_state *scanout_state;
+	struct drm_plane *scanout_plane = output->scanout_plane;
 	struct drm_backend *b = to_drm_backend(c);
 	struct drm_fb *fb;
 
@@ -1440,10 +1441,20 @@ drm_output_render(struct drm_output *output, pixman_region32_t *damage)
 	if (scanout_state->fb)
 		return;
 
-	if (b->use_pixman)
+	if (!pixman_region32_not_empty(damage) &&
+	    scanout_plane->state_cur->fb &&
+	    (scanout_plane->state_cur->fb->type == BUFFER_GBM_SURFACE ||
+	     scanout_plane->state_cur->fb->type == BUFFER_PIXMAN_DUMB) &&
+	    scanout_plane->state_cur->fb->width ==
+		output->base.current_mode->width &&
+	    scanout_plane->state_cur->fb->height ==
+		output->base.current_mode->height) {
+		fb = drm_fb_ref(scanout_plane->state_cur->fb);
+	} else if (b->use_pixman) {
 		fb = drm_output_render_pixman(output, damage);
-	else
+	} else {
 		fb = drm_output_render_gl(output, damage);
+	}
 
 	if (!fb) {
 		drm_plane_state_put_back(scanout_state);
-- 
2.9.3