Re: Corruption in glxgears with Compiz

[Peter Clifton <pcjc2@cam.ac.uk>]

On Fri, 2010-10-22 at 20:29 +0100, Chris Wilson wrote:
> On Fri, 22 Oct 2010 20:10:44 +0100, Peter Clifton <pcjc2@cam.ac.uk> wrote:
> > As an additional data-point, with the bug manifesting, if you go to
> > "expose" mode, (Win+E for default config), you find the corruption is
> > absent. It only appears to be present when the glxgears window is not
> > scaled by the window manager.
> 
> My guess is that it is a double application of the drawable offset when
> doing a CopyRegion swapbuffers. Does the corruption move in relation to
> the window as it moves?
> 
> This suggests that [my] recent changes to the ddx are to blame, and
> certainly a bisection on -intel might help - though it's probably just as
> easy to test before the shadow+dri changes to confirm.
> -Chris

Lost of bisecting and backporting later.. and I've identified the bad
commit:

9220434a8768902cd9cf248709972678b74aa8c1 drm/i915: Only emit a flush
request on the active ring.

I'm not sure what the correct fix is, but a workaround is this:

Actually, I've not tested that yet.. oops. It certainly works with the
if(1) and if (obj->write_domain) bypassing the test for ... &
I915_GEM_GPU_DOMAIN. That wasn't enough alone though, it didn't work
until I changed:

-               if (flush_rings & RING_RENDER)
+               if (1)

Presumably some object is not getting the RENDER_RING added to the
flush_rings field correctly.



git diff HEAD^
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index cf27655..a9d528e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1901,7 +1901,9 @@ i915_gem_flush(struct drm_device *dev,
                drm_agp_chipset_flush(dev);
 
        if ((flush_domains | invalidate_domains) & I915_GEM_GPU_DOMAINS) {
-               if (flush_rings & RING_RENDER)
+//        if (1) {
+//             if (flush_rings & RING_RENDER)
+               if (1)
                        i915_gem_flush_ring(dev,
                                            &dev_priv->render_ring,
                                            invalidate_domains, flush_domains);
@@ -4197,6 +4199,7 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
                 * flush earlier is beneficial.
                 */
                if (obj->write_domain & I915_GEM_GPU_DOMAINS) {
+//             if (obj->write_domain) {
                        i915_gem_flush_ring(dev,
                                            obj_priv->ring,
                                            0, obj->write_domain);



-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)