radv: fix alpha-to-coverage when there is unused color attachments

When alphaToCoverage is enabled, we should always write the alpha
channel of MRT0 if it's unused. This now matches RadeonSI.

This fixes the new CTS:
dEQP-VK.pipeline.multisample.alpha_to_coverage_unused_attachment.samples_*.alpha_invisible

Cc: 19.0 19.1 <mesa-stable@lists.freedesktop.org>
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-By: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl

diff --git a/src/amd/vulkan/radv_pipeline.c b/src/amd/vulkan/radv_pipeline.c
index 895c4fbbb834382774913f862fa85e6a8f8bf77b..6c0d0994cdbf946e010f54f5c2104d1d52d73ed6 100644 (file)
--- a/src/amd/vulkan/radv_pipeline.c
+++ b/src/amd/vulkan/radv_pipeline.c
@@ -523,7 +523,7 @@ radv_pipeline_compute_spi_color_formats(struct radv_pipeline *pipeline,
                col_format |= cf << (4 * i);
        }
 
-       if (!col_format && blend->need_src_alpha & (1 << 0)) {
+       if (!(col_format & 0xf) && blend->need_src_alpha & (1 << 0)) {
                /* When a subpass doesn't have any color attachments, write the
                 * alpha channel of MRT0 when alpha coverage is enabled because
                 * the depth attachment needs it.