i915: Derive the correct target color from the pixmap by checking its format

Particularly noting to route alpha to the green channel when blending
with a8 destinations.

Fixes:

  rendercheck/repeat/triangles regressed
  http://bugs.freedesktop.org/show_bug.cgi?id=25047

introduced with commit 14109a.

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

1 files changed, 6 insertions, 0 deletions

diff --git a/uxa/uxa.h b/uxa/uxa.h
index b1f3737a..c7e5566a 100644
--- a/uxa/uxa.h
+++ b/uxa/uxa.h
@@ -521,6 +521,12 @@ void uxa_driver_fini(ScreenPtr pScreen);
 
 CARD32 uxa_get_pixmap_first_pixel(PixmapPtr pPixmap);
 
+Bool
+uxa_get_color_for_pixmap (PixmapPtr	 pixmap,
+			  CARD32	 src_format,
+			  CARD32	 dst_format,
+			  CARD32	*pixel);
+
 void uxa_set_fallback_debug(ScreenPtr screen, Bool enable);
 
 /**