On 08/05/2012 08:36 AM, Paul Berry wrote: > Just looking for a quick patch review to make sure I've backported > these patches to 8.0 correctly (and also confirmation that this > backport is a good idea). These patches are intended to apply to the > 8.0 branch. > > The issue is that on Gen6 and Gen7, images rendered to depth and > stencil buffers must be aligned to a multiple of 8 pixels, otherwise > certain rendering operations produce a GPU hang. Unfortunately, due > to the layout of miptrees (and the fact that we render to depth and > stencil miptrees using coordinate offsets), it would take a lot of > code rework to both produce correct rendering and guarantee no GPU > hangs. > > These patches avoid the GPU hangs by forcing the image offsets to be > multiples of 8. As a result, correct rendering to depth and stencil > miptrees is sacrificed but the GPU doesn't hang. The sacrifice is > minor, since it only affects miptree levels that would otherwise be > unaligned (in practice this is usually just the smallest miplevels), > and it only matters for (a) rendering to a depth/stencil buffer that > is later used as a texture, or (b) ping-ponging between miplevels > while rendering, both of which are fairly rare. On the master branch, > we decided that this was a worthwhile compromise. > > As a result of this sacrifice, this will regress the following piglit > tests: fbo/fbo-depth-array (Gen6 only), > spec/ARB_depth_buffer_float/fbo-clear-formats, > spec/ARB_depth_texture/fbo-clear-formats, and > spec/EXT_packed_depth_stencil/fbo-clear-formats. These tests > currently fail on master for the same reason. > > For more information see: > https://bugs.freedesktop.org/show_bug.cgi?id=50271 > > [PATCH 1/2] i965/Gen6: Work around GPU hangs due to misaligned depth > coordinate offsets. > [PATCH 2/2] i965/Gen7: Work around GPU hangs due to misaligned depth > coordinate offsets.
This trade-off makes sense to me. Take small amounts of misrendering in a few piglit tests doing non-real-world cases but avoid nasty GPU hangs. I hate to regress Piglit tests on stable, but it's for the best. For some reason, I thought this needed the more invasive coarse/fine-grained tile offset patches. Have you tested this to confirm it fixes the cases? _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
