[Mesa-stable] [PATCH] radv: fix alpha-to-coverage when there is unused color attachments

[Samuel Pitoiset]

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 at lists.freedesktop.org>
Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
---
 src/amd/vulkan/radv_pipeline.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/amd/vulkan/radv_pipeline.c b/src/amd/vulkan/radv_pipeline.c
index d38c56b337e..8bc0d9b53e6 100644
--- 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.
-- 
2.21.0