Re: [PATCH] drm/i915: Cancel hangcheck before GPU is suspended

[Imre Deak <imre.deak@intel.com>]

On Wed, 2015-12-09 at 16:19 +0000, Chris Wilson wrote:
> On Wed, Dec 09, 2015 at 04:10:03PM +0200, Imre Deak wrote:
> > On ke, 2015-12-09 at 15:56 +0200, Joonas Lahtinen wrote:
> > > In order to avoid accessing GPU registers while GPU is suspended
> > > cancel
> > > the hangcheck work before calling intel_suspend_complete which
> > > actually
> > > puts the GPU to suspend. Otherwise hangcheck might do MMIO reads
> > > to a
> > > suspended GPU.
> > > 
> > > Placement before intel_guc_suspend is imitated from
> > > i915_drm_suspend
> > > which cancels the work at i915_gem_suspend, to keep the functions
> > > similar.
> > > 
> > > On VLV systems, namely BYT, this was causing an error during
> > > runtime
> > > suspend cycle:
> > > 
> > > [drm:vlv_check_no_gt_access [i915]] *ERROR* GT register access
> > > while
> > > GT waking disabled
> > > 
> > > Testcase: igt/pm_rpm/basic-rte
> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93121
> > > 
> > > Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > > Cc: Imre Deak <imre.deak@intel.com>
> > > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > 
> > Yep, looks good to me:
> > Reviewed-by: Imre Deak <imre.deak@intel.com>
> 
> Well Imre also shotdown the simple tryget plan, so the only thing I
> can
> say is that I'd rather move the cancel_sync(hangcheck) out of the
> intel_runtime_suspend() into the mark_idle to match it's counterpart
> in
> mark_busy.
> 
> Patch in the post, so for now
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

Pushed to dinq, thanks for the patch and review.


> -Chris
> 
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