Re: [PATCH 00/16] fix VLV S4 suspend/resume, unify S3/S4 handlers

From: Imre Deak <imre.deak@intel.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 00/16] fix VLV S4 suspend/resume, unify S3/S4 handlers
Date: Thu, 11 Sep 2014 16:48:54 +0300	[thread overview]
Message-ID: <1410443334.4879.42.camel@intelbox> (raw)
In-Reply-To: <20140911090222.GH15520@phenom.ffwll.local>

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On Thu, 2014-09-11 at 11:02 +0200, Daniel Vetter wrote:
> On Wed, Sep 10, 2014 at 09:38:50PM +0300, Imre Deak wrote:
> > On Wed, 2014-09-10 at 17:52 +0200, Daniel Vetter wrote:
> > > On Wed, Sep 10, 2014 at 06:16:53PM +0300, Imre Deak wrote:
> > > > The first part of the patchset (1-6) fixes an S4 bug on VLV introduced
> > > > recently. The rest unifies the various S3/S4 handlers, which are in
> > > > practice the same. The only real difference - besides some unused code -
> > > > is that during S3 suspend we disable the PCI device whereas across an S4
> > > > freeze/thaw we keep it enabled. Given that we disable everything else
> > > > anyway, we can just as well disable the PCI device there too. Doing so
> > > > allows us to handle S3 suspend/resume and S4 freeze/thaw/restore/
> > > > power-off the same way, simplifying/clarifying things quite a bit.
> > > 
> > > Hm, this might explain why we've seen random corruption on S4 on recent
> > > platforms.
> > > 
> > > https://bugzilla.kernel.org/show_bug.cgi?id=59321
> > > 
> > > Can you please ask for retesting from reporters?
> > 
> > Ok, can do, I also forgot to add
> > 
> > https://bugs.freedesktop.org/show_bug.cgi?id=82842
> > 
> > which it fixes. I can't see immediately how platforms other than VLV
> > would be fixed with these, but maybe I missed something.
> 
> drm/i915: disable/re-enable PCI device around S4 freeze/thaw
> 
> looks rather generic and not vlv specific, and could very well fix the
> kernel bz I've pasted. Or am I horribly blind?

Yea it's generic, so possibly fixes something. Although by the time we
disable the PCI device in freeze everything should be idle, so if simply
disabling/re-enabling makes a difference then we failed to idle
something. Or we depend on a HW reset (implicit in the
disable/re-enable) before reinitializing things in thaw. Anyway we can
clarify this more once we get feedback from the retesting.

--Imre

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