[Intel-gfx] [REGRESSION] system hang on ILK/SNB/IVB

Lukas Wunner lukas at wunner.de
Wed Mar 30 21:35:08 UTC 2016

Hi Gabriel,

On Wed, Mar 30, 2016 at 08:20:26PM +0300, Gabriel Feceoru wrote:
> This commit causes a hang while running kms suspend tests
> (kms_pipe_crc_basic at suspend-read-crc-pipe-*) on ILK/SNB/IVB, affecting CI.

This happened with v1 but not with v2 of the patch.
Please check if somehow v1 ended up in your tree.

v2 passed CI fine, save for one warning not caused by the patch:

For comparison, this was v1:

Best regards,


> Probably the same problem with the one in v2, but on older HW.
> commit a7442b93cf32c1e1ddb721a26cd1f92302e2a222
> Author: Lukas Wunner <lukas at wunner.de>
> Date:   Wed Mar 9 12:52:53 2016 +0100
>     drm/i915: Fix races on fbdev
>     The ->lastclose callback invokes intel_fbdev_restore_mode() and has
>     been witnessed to run before intel_fbdev_initial_config_async()
>     has finished.
>     We might likewise receive hotplug events before we've had a chance to
>     fully set up the fbdev.
>     Fix by waiting for the asynchronous thread to finish.
>     v2:
>     An async_synchronize_full() was also added to intel_fbdev_set_suspend()
>     in v1 which turned out to be entirely gratuitous. It caused a deadlock
>     on suspend (discovered by CI, thanks to Damien Lespiau and Tomi Sarvela
>     for CI support) and was unnecessary since a device is never suspended
>     until its ->probe callback (and all asynchronous tasks it scheduled)
>     have finished. See dpm_prepare(), which calls wait_for_device_probe(),
>     which calls async_synchronize_full().
>     Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93580
>     Reported-by: Gustav F├Ągerlind <gustav.fagerlind at gmail.com>
>     Reported-by: "Li, Weinan Z" <weinan.z.li at intel.com>
>     Cc: Chris Wilson <chris at chris-wilson.co.uk>
>     Cc: stable at vger.kernel.org
>     Signed-off-by: Lukas Wunner <lukas at wunner.de>
>     Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>     Link: http://patchwork.freedesktop.org/patch/msgid/20160309115147.67B2B6E0D3@gabe.freedesktop.org
> Regards,
> Gabriel

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