panfrost: Disable AFBC on sRGB buffers

The performance impact is slightly mitigated by tiling the render
target, but it's undeniably still slow compared to AFBC. Unfortunately,
it doesn't look like AFBC and sRGB play nice...

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>

src/gallium/drivers/panfrost/pan_afbc.c

@@ -83,6 +83,13 @@ panfrost_format_supports_afbc(enum pipe_format format)
         const struct util_format_description *desc =
                 util_format_description(format);
 
+        /* sRGB cannot be AFBC, but it can be tiled. TODO: Verify. The blob
+         * does not do AFBC for SRGB8_ALPHA8, but it's not clear why it
+         * shouldn't be able to. */
+
+        if (desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB)
+                return false;
+
         if (util_format_is_rgba8_variant(desc))
                 return true;