Only copy from screen pixmap to shared pixmap on demand for slave scanout

Only copy once for each time we update the corresponding scanout pixmap.
This can significantly reduce the bandwidth usage when there are
frequent updates to the screen pixmap.

This initial implementation only works when both the master and slave
screens use this driver.

v2:
* Reduce churn in radeon_prime_scanout_update_handler
* Clear the correct damage in radeon_dirty_update

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 69 insertions, 13 deletions

diff --git a/src/radeon_kms.c b/src/radeon_kms.c
index 51f320cf..711e84a2 100644
--- a/src/radeon_kms.c
+++ b/src/radeon_kms.c
@@ -440,6 +440,9 @@ redisplay_dirty(PixmapDirtyUpdatePtr dirty, RegionPtr region)
 {
 	ScrnInfoPtr pScrn = xf86ScreenToScrn(dirty->src->drawable.pScreen);
 
+	if (RegionNil(region))
+		goto out;
+
 	if (dirty->slave_dst->master_pixmap)
 	    DamageRegionAppend(&dirty->slave_dst->drawable, region);
 
@@ -453,6 +456,7 @@ redisplay_dirty(PixmapDirtyUpdatePtr dirty, RegionPtr region)
 	if (dirty->slave_dst->master_pixmap)
 	    DamageRegionProcessPending(&dirty->slave_dst->drawable);
 
+out:
 	DamageEmpty(dirty->damage);
 }
 
@@ -465,6 +469,39 @@ radeon_prime_scanout_update_abort(xf86CrtcPtr crtc, void *event_data)
 }
 
 void
+radeon_sync_shared_pixmap(PixmapDirtyUpdatePtr dirty)
+{
+    ScreenPtr master_screen = dirty->src->master_pixmap->drawable.pScreen;
+    PixmapDirtyUpdatePtr ent;
+    RegionPtr region;
+
+    xorg_list_for_each_entry(ent, &master_screen->pixmap_dirty_list, ent) {
+	if (ent->slave_dst != dirty->src)
+	    continue;
+
+	region = dirty_region(ent);
+	redisplay_dirty(ent, region);
+	RegionDestroy(region);
+    }
+}
+
+static Bool
+master_has_sync_shared_pixmap(ScrnInfoPtr scrn, PixmapDirtyUpdatePtr dirty)
+{
+    ScrnInfoPtr master_scrn = xf86ScreenToScrn(dirty->src->master_pixmap->drawable.pScreen);
+
+    return master_scrn->driverName == scrn->driverName;
+}
+
+static Bool
+slave_has_sync_shared_pixmap(ScrnInfoPtr scrn, PixmapDirtyUpdatePtr dirty)
+{
+    ScrnInfoPtr slave_scrn = xf86ScreenToScrn(dirty->slave_dst->drawable.pScreen);
+
+    return slave_scrn->driverName == scrn->driverName;
+}
+
+void
 radeon_prime_scanout_update_handler(xf86CrtcPtr crtc, uint32_t frame, uint64_t usec,
 				    void *event_data)
 {
@@ -477,8 +514,12 @@ radeon_prime_scanout_update_handler(xf86CrtcPtr crtc, uint32_t frame, uint64_t u
     xorg_list_for_each_entry(dirty, &screen->pixmap_dirty_list, ent) {
 	if (dirty->src == scanoutpix &&
 	    dirty->slave_dst == drmmode_crtc->scanout[0].pixmap) {
-	    RegionPtr region = dirty_region(dirty);
+	    RegionPtr region;
 
+	    if (master_has_sync_shared_pixmap(scrn, dirty))
+		radeon_sync_shared_pixmap(dirty);
+
+	    region = dirty_region(dirty);
 	    redisplay_dirty(dirty, region);
 	    RegionDestroy(region);
 	    break;
@@ -542,26 +583,41 @@ radeon_prime_scanout_update(PixmapDirtyUpdatePtr dirty)
 }
 
 static void
-radeon_dirty_update(ScreenPtr screen)
+radeon_dirty_update(ScrnInfoPtr scrn)
 {
+	ScreenPtr screen = scrn->pScreen;
 	PixmapDirtyUpdatePtr ent;
-
-	if (xorg_list_is_empty(&screen->pixmap_dirty_list))
-		return;
+	RegionPtr region;
 
 	xorg_list_for_each_entry(ent, &screen->pixmap_dirty_list, ent) {
-		RegionPtr region = dirty_region(ent);
+		if (screen->isGPU) {
+			PixmapDirtyUpdatePtr region_ent = ent;
+
+			if (master_has_sync_shared_pixmap(scrn, ent)) {
+				ScreenPtr master_screen = ent->src->master_pixmap->drawable.pScreen;
 
-		if (RegionNotEmpty(region)) {
-			if (screen->isGPU)
+				xorg_list_for_each_entry(region_ent, &master_screen->pixmap_dirty_list, ent) {
+					if (region_ent->slave_dst == ent->src)
+						break;
+				}
+			}
+
+			region = dirty_region(region_ent);
+
+			if (RegionNotEmpty(region))
 				radeon_prime_scanout_update(ent);
 			else
-				redisplay_dirty(ent, region);
+				DamageEmpty(region_ent->damage);
+
+			RegionDestroy(region);
 		} else {
-			DamageEmpty(ent->damage);
-		}
+			if (slave_has_sync_shared_pixmap(scrn, ent))
+				continue;
 
-		RegionDestroy(region);
+			region = dirty_region(ent);
+			redisplay_dirty(ent, region);
+			RegionDestroy(region);
+		}
 	}
 }
 #endif
@@ -861,7 +917,7 @@ static void RADEONBlockHandler_KMS(BLOCKHANDLER_ARGS_DECL)
     radeon_cs_flush_indirect(pScrn);
 
 #ifdef RADEON_PIXMAP_SHARING
-    radeon_dirty_update(pScreen);
+    radeon_dirty_update(pScrn);
 #endif
 }