[Mesa-dev] [PATCH] gen6-gen7: disable dithering for GL_RGB10_A2 render buffers

[Jordan Justen]

With only 2 bits available, dithering causes undesirable results
for RGB10_A2 render targets.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=74700
Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
---
Tested on Haswell.

We likely need a change for gen8 too. I'll work with Ken on this.

 src/mesa/drivers/dri/i965/gen6_cc.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/gen6_cc.c b/src/mesa/drivers/dri/i965/gen6_cc.c
index 45c926c..c99ee12 100644
--- a/src/mesa/drivers/dri/i965/gen6_cc.c
+++ b/src/mesa/drivers/dri/i965/gen6_cc.c
@@ -63,13 +63,17 @@ gen6_upload_blend_state(struct brw_context *brw)
    for (b = 0; b < nr_draw_buffers; b++) {
       /* _NEW_BUFFERS */
       struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[b];
+      GLenum rb_internal_format;
       GLenum rb_type;
       bool integer;
 
-      if (rb)
+      if (rb) {
 	 rb_type = _mesa_get_format_datatype(rb->Format);
-      else
+         rb_internal_format = rb->InternalFormat;
+      } else {
 	 rb_type = GL_UNSIGNED_NORMALIZED;
+         rb_internal_format = GL_NONE;
+      }
 
       /* Used for implementing the following bit of GL_EXT_texture_integer:
        *     "Per-fragment operations that require floating-point color
@@ -179,7 +183,8 @@ gen6_upload_blend_state(struct brw_context *brw)
       }
 
       /* _NEW_COLOR */
-      if (ctx->Color.DitherFlag && !integer) {
+      if (ctx->Color.DitherFlag && !integer &&
+          rb_internal_format != GL_RGB10_A2) {
 	 blend[b].blend1.dither_enable = 1;
 	 blend[b].blend1.y_dither_offset = 0;
 	 blend[b].blend1.x_dither_offset = 0;
-- 
1.9.rc1