Module: Mesa Branch: master Commit: 61b0cfd84ee6fb1273928ee2c8751301ae805eaa URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=61b0cfd84ee6fb1273928ee2c8751301ae805eaa
Author: Jason Ekstrand <[email protected]> Date: Thu Jan 14 20:42:47 2016 -0800 i965/fs: Always set channel 2 of texture headers in some stages In the vertex and fragment stages, the hardware is nice to us and leaves g0.2 zerod out for us so we can use it for headers. However, in compute, geometry, and tessellation stages, the hardware is not so nice. In particular, for compute shaders on BDW, the hardware places some debug bits in 23:15. As it happens, bit 15 is interpreted by the sampler as the alpha channel mask. This means that if you use a texturing instruction with a header in a compute shader, you may randomly get the alpha channel disabled. Since channel masks affect the return length of the sampler message, this can lead the GPU to expect a different mlen to the one you specified in the shader and this, in turn, hangs your GPU. Cc: "11.1" <[email protected]> Reviewed-by: Jordan Justen <[email protected]> --- src/mesa/drivers/dri/i965/brw_fs_generator.cpp | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp index 741a77b..e05622a 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_generator.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_generator.cpp @@ -913,6 +913,14 @@ fs_generator::generate_tex(fs_inst *inst, struct brw_reg dst, struct brw_reg src /* Set the offset bits in DWord 2. */ brw_MOV(p, get_element_ud(header_reg, 2), brw_imm_ud(inst->offset)); + } else if (stage != MESA_SHADER_VERTEX && + stage != MESA_SHADER_FRAGMENT) { + /* The vertex and fragment stages have g0.2 set to 0, so + * header0.2 is 0 when g0 is copied. Other stages may not, so we + * must set it to 0 to avoid setting undesirable bits in the + * message. + */ + brw_MOV(p, get_element_ud(header_reg, 2), brw_imm_ud(0)); } brw_adjust_sampler_state_pointer(p, header_reg, sampler_index); _______________________________________________ mesa-commit mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/mesa-commit
