[PATCH v2 xserver] glamor: Two pass won't work on memory pixmaps

[Olivier Fourdan]

When selecting "CA_TWO_PASS" in glamor_composite_clipped_region() when
the hardware does not support "GL_ARB_blend_func_extended", we call
glamor_composite_choose_shader() twice in a row, which in turn calls
glamor_pixmap_ensure_fbo().

On memory pixmaps, the first call will set the FBO and the second one
will fail an assertion in glamor_upload_picture_to_texture() because
the FBO is already set.

Bail out earlier when the mask pixmap is in memory and the hardware
capabilities would require to use two pass, so that the assertion is not
failed and the rendering is correct.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99346
Signed-off-by: Olivier Fourdan <ofourdan at redhat.com>
---
 v2: Bail out only on the specific case which would lead to the assertion
     failure otherwise

 glamor/glamor_render.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/glamor/glamor_render.c b/glamor/glamor_render.c
index e04dd21..52f073d 100644
--- a/glamor/glamor_render.c
+++ b/glamor/glamor_render.c
@@ -1494,6 +1494,10 @@ glamor_composite_clipped_region(CARD8 op,
             ca_state = CA_DUAL_BLEND;
         } else {
             if (op == PictOpOver) {
+                if (glamor_pixmap_is_memory(mask_pixmap)) {
+                    glamor_fallback("two pass not supported on memory pximaps\n");
+                    goto out;
+                }
                 ca_state = CA_TWO_PASS;
                 op = PictOpOutReverse;
             }
-- 
2.9.3