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

[Gabriel Feceoru]

On 31.03.2016 00:35, Lukas Wunner wrote:
> 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.

It's v2.

Tomi already replied, meantime I also looked at the results.
The current regression is for ILK/SNB/IVB only (v1 seemed to affect more 
platforms).
Unfortunately these machines were not available when v2 was tested, so 
this couldn't be detected.

Regards,
Gabriel.

>
> v2 passed CI fine, save for one warning not caused by the patch:
> https://patchwork.freedesktop.org/series/4068/
>
> For comparison, this was v1:
> https://patchwork.freedesktop.org/patch/75840/
>
> Best regards,
>
> Lukas
>
>>
>> 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 Fägerlind <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