[Nouveau] [regression drm/noveau] suspend to ram -> BOOM: exception RIP: drm_calc_vbltimestamp_from_scanoutpos+335

[Karol Herbst]

Yeah, we shouldn't let the machine die. Are there more WARN_ON_ONCE
usage we could convert to WARN_ONCE?

Reviewed-By: Karol Herbst <karolherbst at gmail.com>

On Fri, Jul 14, 2017 at 5:05 PM, Tobias Klausmann
<tobias.johannes.klausmann at mni.thm.de> wrote:
> On 7/14/17 3:41 PM, Mike Galbraith wrote:
>>
>> On Fri, 2017-07-14 at 15:36 +0200, Mike Galbraith wrote:
>>>
>>>   All DRM did was to slip a
>>> WARN_ON_ONCE() that nouveau triggers into a kernel module where such
>>> things no longer warn, they blow the box out of the water.
>>
>> BTW, turn that irksome WARN_ON_ONCE() in drivers/gpu/drm/drm_vblank.c
>> into a WARN_ONCE(), and all is peachy, you get the warning, box lives.
>>
>> ---
>>   drivers/gpu/drm/drm_vblank.c |    3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> --- a/drivers/gpu/drm/drm_vblank.c
>> +++ b/drivers/gpu/drm/drm_vblank.c
>> @@ -605,7 +605,8 @@ bool drm_calc_vbltimestamp_from_scanoutp
>>          */
>>         if (mode->crtc_clock == 0) {
>>                 DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n",
>> pipe);
>> -               WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev));
>> +               WARN_ONCE(drm_drv_uses_atomic_modeset(dev), "%s: report
>> me.\n",
>> +                         dev->driver->name);
>>                 return false;
>>         }
>
>
>
> Hey,
>
> confirmed this helps saving the box, but we still have to find the root
> cause! Backtrace with the above fix applied (and the one which came in with
> the latest drm-fixes merge)!
>
>
> [1] https://hastebin.com/uyoqifijed.http
>
> Thanks,
>
> Tobias
>Reviewed-By: Karol Herbst <karolherbst at gmail.com>
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