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

[Mike Galbraith]

On Fri, 2017-07-14 at 17:05 +0200, Tobias Klausmann 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)!

Yeah, I'll be reporting some extra whining from my 8600 GT backup box.

	-Mike