Am Montag, den 18.07.2011, 00:55 -0700 schrieb Chad Versace: > 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.
The alignment does not seem to match. > */ > if (attachment == DRI2BufferStencil) { > - pixmap_height /= 2; > + pixmap_width = ALIGN(pixmap_width, 64); > + pixmap_height = ALIGN(pixmap_height / 2, 64); > pixmap_cpp *= 2; > } Thanks, Paul
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