[Mesa-dev] [PATCH] nvc0: Disable BGRA8 images on Fermi

[Lyude]

For unknown reasons, using BGRA8 images on Fermi results in breaking
reads from PBOs, such that they always return 0x0. Discovered this
through a glamor bug, and confirmed it does indeed break a good number
of piglit tests such as spec/arb_pixel_buffer_object/pbo-read-argb8888

Until we have a proper fix, just disable this functionality on Fermi.

Signed-off-by: Lyude <lyude at redhat.com>
---
 src/gallium/drivers/nouveau/nvc0/nvc0_screen.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c b/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
index c636926..f6c5c72 100644
--- a/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
+++ b/src/gallium/drivers/nouveau/nvc0/nvc0_screen.c
@@ -87,11 +87,20 @@ nvc0_screen_is_format_supported(struct pipe_screen *pscreen,
    bindings &= ~(PIPE_BIND_LINEAR |
                  PIPE_BIND_SHARED);
 
-   if (bindings & PIPE_BIND_SHADER_IMAGE && sample_count > 1 &&
-       nouveau_screen(pscreen)->class_3d >= GM107_3D_CLASS) {
-      /* MS images are currently unsupported on Maxwell because they have to
-       * be handled explicitly. */
-      return false;
+   if (bindings & PIPE_BIND_SHADER_IMAGE) {
+      if (sample_count > 1 &&
+          nouveau_screen(pscreen)->class_3d >= GM107_3D_CLASS) {
+         /* MS images are currently unsupported on Maxwell because they have to
+          * be handled explicitly. */
+         return false;
+      }
+
+      if (format == PIPE_FORMAT_B8G8R8A8_UNORM &&
+          nouveau_screen(pscreen)->class_3d < NVE4_3D_CLASS) {
+         /* This should work on Fermi, but for currently unknown reasons it
+          * does not and results in breaking reads from pbos. */
+         return false;
+      }
    }
 
    return (( nvc0_format_table[format].usage |
-- 
2.9.4