Until now, the stencil buffer was allocated as a Y tiled buffer, because
in several locations the PRM states that it is. However, it is actually
W tiled. From the PRM, 2011 Sandy Bridge, Volume 1, Part 2, Section
4.5.2.1 W-Major Format:
W-Major Tile Format is used for separate stencil.
The GTT is incapable of W fencing, so we allocate the stencil buffer with
I915_TILING_NONE and decode the tile's layout in software.
This commit mutually depends on the mesa commit:
intel: Fix stencil buffer to be W tiled
Author: Chad Versace <c...@chad-versace.us>
Date: Mon Jul 18 00:37:45 2011 -0700
CC: Eric Anholt <e...@anholt.net>
CC: Kenneth Graunke <kenn...@whitecape.org>
Signed-off-by: Chad Versace <c...@chad-versace.us>
---
src/intel_dri.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/src/intel_dri.c b/src/intel_dri.c
index 5ea7c2c..4652dc7 100644
--- a/src/intel_dri.c
+++ b/src/intel_dri.c
@@ -336,7 +336,6 @@ I830DRI2CreateBuffer(DrawablePtr drawable, unsigned int
attachment,
switch (attachment) {
case DRI2BufferDepth:
case DRI2BufferDepthStencil:
- case DRI2BufferStencil:
case DRI2BufferHiz:
if (SUPPORTS_YTILING(intel)) {
hint |= INTEL_CREATE_PIXMAP_TILING_Y;
@@ -351,6 +350,14 @@ I830DRI2CreateBuffer(DrawablePtr drawable, unsigned int
attachment,
case DRI2BufferFrontRight:
hint |= INTEL_CREATE_PIXMAP_TILING_X;
break;
+ case DRI2BufferStencil:
+ /*
+ * The stencil buffer is W tiled. However, we
+ * request from the kernel a non-tiled buffer
+ * because the GTT is incapable of W fencing.
+ */
+ hint |= INTEL_CREATE_PIXMAP_TILING_NONE;
+ break;
default:
free(privates);
free(buffer);
@@ -368,11 +375,12 @@ I830DRI2CreateBuffer(DrawablePtr drawable, unsigned int
attachment,
* To accomplish this, we resort to the nasty hack of doubling
* the drm region's cpp and halving its height.
*
- * If we neglect to double the pitch, then
- * drm_intel_gem_bo_map_gtt() maps the memory incorrectly.
+ * If we neglect to double the pitch, then render corruption
+ * occurs.
*/
if (attachment == DRI2BufferStencil) {
- pixmap_height /= 2;
+ pixmap_width = ALIGN(pixmap_width, 64);
+ pixmap_height = ALIGN(pixmap_height / 2, 64);
pixmap_cpp *= 2;
}
--
1.7.6
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