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dri: Do not tile stencil buffer 

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 <chad@chad-versace.us>
    Date:   Mon Jul 18 00:37:45 2011 -0700

Signed-off-by: Chad Versace <chad@chad-versace.us>
Reviewed-by: Ian Romanick <ian.romanick@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Chad Versace 2011-07-18 00:38:00 -07:00
parent 212fa98687
commit 3e55f3e88b
1 changed files with 12 additions and 4 deletions
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16
src/intel_dri.c
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@ -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 + 1) / 2, 64);
pixmap_cpp *= 2;
}