[DC] [CRTC:44:crtc-0] vblank wait timed out

[Andrey Grodzovsky]

On 11/14/2017 01:06 PM, Michel Dänzer wrote:
> I sometimes get the attached dmesg splat when the GDM login screen times
> out and fades to black (presumably specifically when it finally sets
> DPMS off, which disables the vblank interrupt).

As you mention this and also that this happens intermittently I would 
suspect a race between page flip and DPMS(OFF) IOCTLs so by the time 
drm_atomic_helper_wait_for_vblanks is called from  page flip the DPMS 
IOCTL already turned vblank off, but do_aquire_global_lock should 
protect exactly from such a race so maybe something broke around there. 
Maybe putting  a WARN_ON(vblank interrupt status != ON) before waiting 
on it can shed some light on this.

Thanks,
Andrey

>
> I've seen this for the first time today, so it might have been
> introduced by one of the DC changes which landed in amd-staging-drm-next
> since yesterday. But since it doesn't happen every time, I can't be sure
> of that yet.
>
>