Re: Graphical corruption post 2.6.38

[Chris Wilson <chris@chris-wilson.co.uk>]

On Wed, 23 Mar 2011 13:54:11 +0000, Colin Guthrie <intel@colin.guthr.ie> wrote:
> Hi,
> 
> Running latest drivers from git + recent drm+xserver.
> 
> After upgrading to 2.6.38 I seem to get occasional graphical corruption.
> This manifests itself mostly obviously in e.g gnome-terminal when
> getting git status and such like (although there are many other triggers
> - have seen it in various apps).
> 
> Here is an example of what it looks like, but it can be much worse.
> http://colin.guthr.ie/intel-2.6.38.png
> 
> Any idea of what could cause this before I go digging too deeply?

First try:

commit 29c5a587284195278e233eec5c2234c24fb2c204
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Thu Mar 17 15:23:22 2011 +0000

    drm/i915: Fix tiling corruption from pipelined fencing
    
    ... even though it was disabled. A mistake in the handling of fence reuse
    caused us to skip the vital delay of waiting for the object to finish
    rendering before changing the register. This resulted in us changing the
    fence register whilst the bo was active and so causing the blits to
    complete using the wrong stride or even the wrong tiling. (Visually the
    effect is that small blocks of the screen look like they have been
    interlaced). The fix is to wait for the GPU to finish using the memory
    region pointed to by the fence before changing it.
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=34584
    Cc: Andy Whitcroft <apw@canonical.com>
    Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
    Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
    [Note for 2.6.38-stable, we need to reintroduce the interruptible passing]
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
    Tested-by: Dave Airlie <airlied@linux.ie>

Thanks,
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre