linux-kernel - Re: [regression drm/noveau] suspend to ram -> BOOM: exception RIP: drm_calc_vbltimestamp_from

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Date:   Fri, 14 Jul 2017 17:05:31 +0200
From:   Tobias Klausmann <tobias.johannes.klausmann@....thm.de>
To:     Mike Galbraith <efault@....de>, Ilia Mirkin <imirkin@...m.mit.edu>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Ben Skeggs <bskeggs@...hat.com>
Subject: Re: [regression drm/noveau] suspend to ram -> BOOM: exception RIP:
 drm_calc_vbltimestamp_from_scanoutpos+335

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