We found out that some HW changes on Xe2 make the HW avoid reading the
blend state if we're using the null_rt bit in the extended descriptor.
Since the alpha_to_coverage bit resides in the blend state, that state
is ignored and writes are going through to the depth/stencil buffers.
Disable null_rt in the color outputs if the color outputs can affect
other outputs (through alpha_to_coverage & omask).
Fixes tests in this pattern on Xe2 :
dEQP-VK.pipeline.*.multisample.alpha_to_coverage_no_color_attachment.*
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Backport-to: 24.2
Reviewed-by: Ivan Briano <ivan.briano@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31196>
(cherry picked from commit 35ea8b6cd2)
951ffef8ab