panfrost: Emit blend descriptors on Bifrost

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4724>
diff --git a/src/panfrost/encoder/pan_format.c b/src/panfrost/encoder/pan_format.c
index 873c4d2..408f815 100644
--- a/src/panfrost/encoder/pan_format.c
+++ b/src/panfrost/encoder/pan_format.c
@@ -275,3 +275,20 @@
                 out[idx] = PIPE_SWIZZLE_X + c;
         }
 }
+
+enum mali_format
+panfrost_format_to_bifrost_blend(const struct util_format_description *desc)
+{
+        enum mali_format format = panfrost_find_format(desc);
+
+        switch (format) {
+        case MALI_RGBA4_UNORM:
+                return MALI_RGBA4;
+        case MALI_RGBA8_UNORM:
+                return MALI_RGBA8_2;
+        case MALI_RGB10_A2_UNORM:
+                return MALI_RGB10_A2_2;
+        default:
+                return format;
+        }
+}