[Mesa-dev] [PATCH] mesa/st: Fix piglit read-front with new drawable invalidation

[Thomas Hellstrom]

When the state tracker adds a front buffer, nothing triggers a validate
drawable call, since the state tracker manager is never notified.

Force a validate drawable call by invalidating the framebuffer's stamp, so
that the window system's renderbuffer (if any) is picked up.

This fixes bug 38988
https://bugs.freedesktop.org/show_bug.cgi?id=38988

Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
---
 src/mesa/state_tracker/st_manager.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/src/mesa/state_tracker/st_manager.c b/src/mesa/state_tracker/st_manager.c
index a8c4b5c..d04db8b 100644
--- a/src/mesa/state_tracker/st_manager.c
+++ b/src/mesa/state_tracker/st_manager.c
@@ -196,7 +196,7 @@ st_framebuffer_validate(struct st_framebuffer *stfb,
 
       stfb->iface_stamp = new_stamp;
       new_stamp = p_atomic_read(&stfb->iface->stamp);
-   } while(stfb->iface_stamp != new_stamp);
+   } while(0);
 
    width = stfb->Base.Width;
    height = stfb->Base.Height;
@@ -918,6 +918,15 @@ st_manager_add_color_renderbuffer(struct st_context *st,
       return FALSE;
 
    st_framebuffer_update_attachments(stfb);
+
+   /*
+    * Force a call to the state tracker manager to validate the
+    * new renderbuffer. It might be that there is a window system
+    * renderbuffer available.
+    */
+   if(stfb->iface)
+      stfb->iface_stamp = p_atomic_read(&stfb->iface_stamp) - 1;
+
    st_invalidate_state(st->ctx, _NEW_BUFFERS);
 
    return TRUE;
-- 
1.6.2.5