sna: Just do a pointer exchange when flipping with no scanout

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

3 files changed, 50 insertions, 13 deletions

diff --git a/src/sna/sna.h b/src/sna/sna.h
index 7456f05a..ae8e5548 100644
--- a/src/sna/sna.h
+++ b/src/sna/sna.h
@@ -274,6 +274,8 @@ extern int sna_do_pageflip(struct sna *sna,
 			    PixmapPtr *old_front,
 			    uint32_t *old_fb);
 
+extern PixmapPtr sna_set_screen_pixmap(struct sna *sna, PixmapPtr pixmap);
+
 void sna_mode_delete_fb(struct sna *sna, PixmapPtr pixmap, uint32_t fb);
 
 static inline struct sna *
diff --git a/src/sna/sna_display.c b/src/sna/sna_display.c
index e893a370..c2347ef3 100644
--- a/src/sna/sna_display.c
+++ b/src/sna/sna_display.c
@@ -1523,6 +1523,20 @@ static int do_page_flip(struct sna *sna, void *data, int ref_crtc_hw_id)
 	return count;
 }
 
+PixmapPtr sna_set_screen_pixmap(struct sna *sna, PixmapPtr pixmap)
+{
+	PixmapPtr old = sna->front;
+	ScrnInfoPtr scrn = sna->scrn;
+
+	sna->front = pixmap;
+	pixmap->refcnt++;
+
+	sna_redirect_screen_pixmap(scrn, old, sna->front);
+	scrn->displayWidth = sna_pixmap_get_bo(pixmap)->pitch / sna->mode.cpp;
+
+	return old;
+}
+
 int
 sna_do_pageflip(struct sna *sna,
 		PixmapPtr pixmap,
diff --git a/src/sna/sna_dri.c b/src/sna/sna_dri.c
index 14a2f3d1..75e2c444 100644
--- a/src/sna/sna_dri.c
+++ b/src/sna/sna_dri.c
@@ -670,7 +670,8 @@ can_flip(struct sna * sna,
 
 	ScreenPtr screen = draw->pScreen;
 
-	assert(draw->type == DRAWABLE_WINDOW);
+	if (draw->type == DRAWABLE_PIXMAP)
+		return FALSE;
 
 	if (front->format != back->format) {
 		DBG(("%s: no, format mismatch, front = %d, back = %d\n",
@@ -969,10 +970,30 @@ sna_dri_schedule_swap(ClientPtr client, DrawablePtr draw, DRI2BufferPtr front,
 	     (long long)divisor,
 	     (long long)remainder));
 
+	flip = 0;
+	if (can_flip(sna, draw, front, back)) {
+		DBG(("%s: can flip\n", __FUNCTION__));
+		swap_type = DRI2_FLIP;
+		flip = 1;
+	}
+
 	/* Drawable not displayed... just complete the swap */
 	pipe = sna_dri_get_pipe(draw);
-	if (pipe == -1)
-		goto blit_fallback;
+	if (pipe == -1) {
+		struct sna_dri_private *back_priv = back->driverPrivate;
+		PixmapPtr pixmap;
+
+		if (!flip)
+			goto blit_fallback;
+
+		pixmap = sna_set_screen_pixmap(sna, back_priv->pixmap);
+		pixmap->refcnt--;
+		assert(pixmap->refcnt > 0);
+		sna_dri_exchange_buffers(draw, front, back);
+		DRI2SwapComplete(client, draw, 0, 0, 0,
+				 DRI2_EXCHANGE_COMPLETE, func, data);
+		return TRUE;
+	}
 
 	/* Truncate to match kernel interfaces; means occasional overflow
 	 * misses, but that's generally not a big deal */
@@ -1002,13 +1023,6 @@ sna_dri_schedule_swap(ClientPtr client, DrawablePtr draw, DRI2BufferPtr front,
 	sna_dri_reference_buffer(front);
 	sna_dri_reference_buffer(back);
 
-	flip = 0;
-	if (can_flip(sna, draw, front, back)) {
-		DBG(("%s: can flip\n", __FUNCTION__));
-		swap_type = DRI2_FLIP;
-		flip = 1;
-	}
-
 	info->type = swap_type;
 	if (divisor == 0)
 		goto immediate;
@@ -1155,9 +1169,7 @@ sna_dri_async_swap(ClientPtr client, DrawablePtr draw,
 
 	DBG(("%s()\n", __FUNCTION__));
 
-	/* Drawable not displayed... just complete the swap */
-	pipe = sna_dri_get_pipe(draw);
-	if (pipe == -1 || !can_flip(sna, draw, front, back)) {
+	if (!can_flip(sna, draw, front, back)) {
 		BoxRec box, *boxes;
 		int n;
 
@@ -1194,6 +1206,15 @@ sna_dri_async_swap(ClientPtr client, DrawablePtr draw,
 		return;
 	}
 
+	pipe = sna_dri_get_pipe(draw);
+	if (pipe == -1) {
+		/* Drawable not displayed... just complete the swap */
+		pixmap = sna_set_screen_pixmap(sna, back_priv->pixmap);
+		pixmap->refcnt--;
+		assert(pixmap->refcnt > 0);
+		goto exchange;
+	}
+
 	if (!sna->dri.flip_pending[pipe]) {
 		struct sna_dri_frame_event *info;
 		DRI2BufferPtr t;