[Intel-gfx] [PATCH] DRI2 CopyRegion scanline wait fixes

[Jesse Barnes]

In the case of full height blits, we were getting tearing on the first line.
This could be due to batch buffer startup time or late vblank events.  On 965
and above we have a "start of vblank" event (as opposed to the one that comes
in after various in-chip housekeeping is done on pre-965), so we can use that
for full screen copies.  For pre-965, we just have to set a scanline wait for
somewhere near the bottom of the screen to give us time to set up the copy.

Fixes bug #22475.

Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>

diff --git a/src/i830_dri.c b/src/i830_dri.c
index 98c1a15..313cc96 100644
--- a/src/i830_dri.c
+++ b/src/i830_dri.c
@@ -302,6 +302,7 @@ I830DRI2CopyRegion(DrawablePtr drawable, RegionPtr pRegion,
 		int y1, y2;
 		int pipe = -1, event, load_scan_lines_pipe;
 		xf86CrtcPtr crtc;
+		Bool full_height = FALSE;
 
 		box = REGION_EXTENTS(unused, gc->pCompositeClip);
 		crtc = i830_covering_crtc(scrn, box, NULL, &crtcbox);
@@ -310,21 +311,34 @@ I830DRI2CopyRegion(DrawablePtr drawable, RegionPtr pRegion,
 		if (crtc != NULL && !crtc->rotatedData) {
 			pipe = i830_crtc_to_pipe(crtc);
 
+			/* Make sure we don't wait for a scanline that will never occur */
+			y1 = (crtcbox.y1 <= box->y1) ? box->y1 - crtcbox.y1 : 0;
+			y2 = (box->y2 <= crtcbox.y2) ?
+			    box->y2 - crtcbox.y1 : crtcbox.y2 - crtcbox.y1;
+
+			if (y1 == 0 && y2 == crtcbox.y2)
+			    full_height = TRUE;
+
+			/* Pre-965 doesn't have SVBLANK, so we need a bit
+			 * of extra time for the blitter to start up and
+			 * do its job for a full height blit */
+			if (full_height && !IS_I965G(intel))
+			    y2 -= 2;
+
 			if (pipe == 0) {
 				event = MI_WAIT_FOR_PIPEA_SCAN_LINE_WINDOW;
 				load_scan_lines_pipe =
 				    MI_LOAD_SCAN_LINES_DISPLAY_PIPEA;
+				if (full_height && IS_I965G(intel))
+				    event = MI_WAIT_FOR_PIPEA_SVBLANK;
 			} else {
 				event = MI_WAIT_FOR_PIPEB_SCAN_LINE_WINDOW;
 				load_scan_lines_pipe =
 				    MI_LOAD_SCAN_LINES_DISPLAY_PIPEB;
+				if (full_height && IS_I965G(intel))
+				    event = MI_WAIT_FOR_PIPEB_SVBLANK;
 			}
 
-			/* Make sure we don't wait for a scanline that will never occur */
-			y1 = (crtcbox.y1 <= box->y1) ? box->y1 - crtcbox.y1 : 0;
-			y2 = (box->y2 <= crtcbox.y2) ?
-			    box->y2 - crtcbox.y1 : crtcbox.y2 - crtcbox.y1;
-
 			BEGIN_BATCH(5);
 			/* The documentation says that the LOAD_SCAN_LINES command
 			 * always comes in pairs. Don't ask me why. */