Bug 23102 - [bisected] i915 regression in post 2.6.36 kernels
Summary: [bisected] i915 regression in post 2.6.36 kernels
Alias: None
Product: Drivers
Classification: Unclassified
Component: Video(DRI - Intel) (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: drivers_video-dri-intel@kernel-bugs.osdl.org
Depends on:
Blocks: 21782
  Show dependency tree
Reported: 2010-11-17 18:16 UTC by Maciej Rutecki
Modified: 2011-02-02 23:44 UTC (History)
7 users (show)

See Also:
Kernel Version: 2.6.37-rc1
Regression: Yes
Bisected commit-id:


Description Maciej Rutecki 2010-11-17 18:16:09 UTC
Subject    : [bisected] i915 regression in post 2.6.36 kernels
Submitter  : Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de>
Date       : 2010-11-10 7:02
Message-ID : 201011100802.20332.johannes.hirte@fem.tu-ilmenau.de
References : http://marc.info/?l=linux-kernel&m=128937310017057&w=2

This entry is being used for tracking a regression from 2.6.36. Please don't
close it until the problem is fixed in the mainline.
Comment 1 Chris Wilson 2010-12-16 14:14:55 UTC
commit de18a29e0fa3904894b4e02fae0e712cd43f740c
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sat Nov 27 22:30:41 2010 +0100

    drm/i915: fix regression due to ba3d8d749b01548b9
    We don't track gpu flush request in any special way. So even with
    obj->write_domain == 0, a gpu flush might be outstanding but no
    yet executed. Even worse, the latest request might use the object
    only for reading. So and unconditional call to object_wait_rendering
    is needed for !pipelined.
    Hence revert that patch fully and untangle the flushing from the
    synchronization again.
    Reported-by: Keith Packard <keithp@keithp.com>
    Tested-by: Keith Packard <keithp@keithp.com>
    Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Comment 2 Johannes Hirte 2010-12-17 19:24:50 UTC
Sorry, but this didn't fixed it for me. The regression still exists, so please reopen.
Comment 3 Florian Mickler 2010-12-17 20:28:09 UTC
Chris, Johannes said in the thread referenced above:

> I've found it. 5c12a07e8073295ce8b57a822f811ac34e4f8420 contains
>  static void
> @@ -1945,11 +1933,6 @@ i915_gem_flush_ring(struct drm_device *dev,
>  {
>       ring->flush(dev, ring, invalidate_domains, flush_domains);
>       i915_gem_process_flushing_list(dev, flush_domains, ring);
> -
> -     if (ring->outstanding_lazy_request) {
> -             (void)i915_add_request(dev, file_priv, NULL, ring);
> -             ring->outstanding_lazy_request = false;
> -     }
>  }
> which wasn't redone by a56ba56c275b1c2b982c8901ab92bf5a0fd0b757. After adding
> those five lines it works for me.
> regards,
>   Johannes

Can you make anything out of that?
Comment 4 Chris Wilson 2010-12-22 12:37:02 UTC
That would be a bug in the kernel that caused the emission of two requests for each batchbuffer. Hence it was removed.
Comment 5 Johannes Hirte 2010-12-22 22:39:30 UTC
Ok, but without this I get the regression, I've reported. Any idea what's going wrong there? The system is unusable with KDE for me.
Comment 6 Johannes Hirte 2010-12-23 02:34:12 UTC
I've tested with gdm instead kdm now and this works. All windows are displayed, in gdm and the started KDE session. With kdm still only the background is showed.
Comment 7 Johannes Hirte 2010-12-23 14:52:44 UTC
There are also problems when logging in via gdm. After some time the screen got completely frozen. Only the mouse was updated but no windows/background.
Comment 8 Florian Mickler 2011-01-05 22:13:29 UTC
Can you observe theses misbehaviours also in the final 2.6.37 kernel?
Comment 9 Johannes Hirte 2011-01-06 21:51:21 UTC
yes it's still present in 2.6.37
Comment 10 Andreas Eckstein 2011-01-07 13:47:01 UTC
I was bitten by this bug too (actually it happened _sometimes_ with 2.6.36.x), but it went away once I upgraded to xf86-video-intel-2.13.903. I cannot guarantee that it won't happen again sometimes though. Will report back if it does.
Comment 11 Johannes Hirte 2011-01-07 22:58:47 UTC
Yes, I can confirm that 2.6.37 works with the latest git of xf86-video-intel. So >xf86-video-intel-2.13 is necessary for 2.6.37 and later.
Comment 12 Chris Wilson 2011-01-14 17:13:47 UTC
Just one of the many userspace flushing issues.

Note You need to log in before you can comment on or make changes to this bug.