Re: [PATCH] drm/i915: Suppress hotplug work during PM suspend/resume

Takashi Iwai
2012-05-10T09:19:12Z

At Thu, 10 May 2012 11:06:46 +0200,
Daniel Vetter wrote:
>
> On Thu, May 10, 2012 at 10:40:52AM +0200, Takashi Iwai wrote:
> > At Thu, 10 May 2012 10:29:19 +0200,
> > Daniel Vetter wrote:
> > >
> > > On Thu, May 10, 2012 at 08:34:43AM +0200, Takashi Iwai wrote:
> > > > At Wed, 25 Apr 2012 10:14:51 +0200,
> > > > Takashi Iwai wrote:
> > > > >
> > > > > At Thu, 19 Apr 2012 20:11:53 +0200,
> > > > > Takashi Iwai wrote:
> > > > > >
> > > > > > At Thu, 19 Apr 2012 13:55:04 -0400,
> > > > > > Adam Jackson wrote:
> > > > > > >
> > > > > > > On Thu, 2012-04-19 at 18:10 +0200, Takashi Iwai wrote:
> > > > > > >
> > > > > > > > This patch adds a flag to disable the hotplug during PM operation for
> > > > > > > > avoiding such a race.
> > > > > > > >
> > > > > > > > Cc: <stable@kernel.org>
> > > > > > > > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > > > > > >
> > > > > > > This seems simpler (untested):
> > > > > >
> > > > > > This looks promising. I'll ask a test with your patch.
> > > > >
> > > > > Tester reported a positive feedback. But he also experienced with a
> > > > > blank screen after a couple of S4 resumes. Now it's being checked
> > > > > whether it's a regression by the patch or not.
> > > >
> > > > It seems unrelated with the patch itself. So, from my side,
> > > > Reviewed-by: Takashi Iwai <tiwai@suse.de>
> > > >
> > > > Adam, could you resubmit it with a proper sign-off so that it can be
> > > > merged for 3.4 or 3.5, preferably with Cc to stable kernel?
> > >
> > > Note that
> > >
> > > daniel@phenom:~/linux/src$ git show
> > > 8b2e326dc7c5aa6952c88656d04d0d81fd85a6f8
> > > commit 8b2e326dc7c5aa6952c88656d04d0d81fd85a6f8
> > > Author: Chris Wilson <chris@chris-wilson.co.uk>
> > > Date: Tue Apr 24 22:59:41 2012 +0100
> > >
> > > drm/i915: Unconditionally initialise the interrupt workers
> > >
> > > in drm-intel-next is closes a race around suspend/resume that could lead
> > > to an oops somewhere on resume.
> >
> > I don't think it's missing hotplug initializations. It's no Oops but
> > the race between the resume procedure being processed and the hotplug
> > work triggered during the resume procedure.
>
> This patch is not just for hotplug, but for all the delayed work and timer
> stuff the driver does. And we _do_ have a bug report that leaking the rps
> work (for snb+ turbo mode) across either a s/r cycle or a gpu reset kills
> the driver.

Yes, but my point is that Chris's patch (at least the commit above
alone) won't fix the problem we faced.

Takashi