xf86-video-intel: src/intel_dri.c

[Chris Wilson]

 src/intel_dri.c |    6 ++++++
 1 file changed, 6 insertions(+)

New commits:
commit 014fc7abb7b2cc2110e3ab9a0bd6f7cff2c64c05
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Wed Mar 9 17:10:50 2011 +0000

    dri: Disable page-flip between a tiled buffer and a linear scanout
    
    Keith Packard pointed out a loophole that could cause the DDX to end up
    with a tiled scanout even if the user required a linear framebuffer;
    that is by using page-flipping we could replace the scanout pixmap with
    another of our choosing, and not necessarily tiled.
    
    Close that loophole by only allowing an exchange of buffers between
    identical tiling modes. For the common case, this is fine since they
    will indeed be allocated with the same tiling. For the linear
    framebuffer case with mesa using a tiled pixmap, we force it to blit
    onto the scanout instead.
    
    Reported-by: Keith Packard <keith.packard at intel.com>
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

diff --git a/src/intel_dri.c b/src/intel_dri.c
index 3901aae..7449232 100644
--- a/src/intel_dri.c
+++ b/src/intel_dri.c
@@ -674,6 +674,8 @@ can_exchange(DRI2BufferPtr front, DRI2BufferPtr back)
 	I830DRI2BufferPrivatePtr back_priv = back->driverPrivate;
 	PixmapPtr front_pixmap = front_priv->pixmap;
 	PixmapPtr back_pixmap = back_priv->pixmap;
+	struct intel_pixmap *front_intel = intel_get_pixmap_private(front_pixmap);
+	struct intel_pixmap *back_intel = intel_get_pixmap_private(back_pixmap);
 
 	if (front_pixmap->drawable.width != back_pixmap->drawable.width)
 		return FALSE;
@@ -690,6 +692,10 @@ can_exchange(DRI2BufferPtr front, DRI2BufferPtr back)
 		return FALSE;
 #endif
 
+	/* prevent an implicit tiling mode change */
+	if (front_intel->tiling != back_intel->tiling)
+		return FALSE;
+
 	return TRUE;
 }