[Intel-gfx] [PATCH] drm/i915/guc: Skip suspend/resume GuC action on platforms w/o GuC submission

[Hiatt, Don]

> From: Ceraolo Spurio, Daniele <daniele.ceraolospurio at intel.com>
> Sent: Friday, November 15, 2019 2:02 PM
> To: Hiatt, Don <don.hiatt at intel.com>; intel-gfx at lists.freedesktop.org
> Cc: Ewins, Jon <jon.ewins at intel.com>; KiteStramuort
> <kitestramuort at autistici.org>; S . Zharkoff <s.zharkoff at gmail.com>;
> Wajdeczko, Michal <Michal.Wajdeczko at intel.com>; Summers, Stuart
> <stuart.summers at intel.com>; Chris Wilson <chris at chris-wilson.co.uk>; Tomas
> Janousek <tomi at nomi.cz>
> Subject: Re: [PATCH] drm/i915/guc: Skip suspend/resume GuC action on
> platforms w/o GuC submission
> 
> 
> 
> On 11/15/19 10:20 AM, don.hiatt at intel.com wrote:
> > From: Don Hiatt <don.hiatt at intel.com>
> >
> > On some platforms (e.g. KBL) that do not support GuC submission, but
> > the user enabled the GuC communication (e.g for HuC authentication)
> > calling the GuC EXIT_S_STATE action results in lose of ability to
> > enter RC6. We can remove the GuC suspend/resume entirely as we do
> > not need to save the GuC submission status.
> >
> > Add intel_guc_submission_is_enabled() function to determine if
> > GuC submission is active.
> >
> > v2: Do not suspend/resume the GuC on platforms that do not support
> >      Guc Submission.
> > v3: Fix typo, move suspend logic to remove goto.
> > v4: Use intel_guc_submission_is_enabled() to check GuC submission
> >      status.
> > v5: No need to look at engine to determine if submission is enabled.
> >      Squash fix + intel_guc_submission_is_enabled() patch into one.
> >
> > Reported-by: KiteStramuort <kitestramuort at autistici.org>
> > Reported-by: S. Zharkoff <s.zharkoff at gmail.com>
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111594
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111623
> > Fixes: f774f0964919 ("drm/i915/guc: Turn on GuC/HuC auto mode")
> 
> I don't think this Fixes tag is appropriate since we already reverted
> that patch.
> 

Can you suggest an appropriate tag? Chris suggest "guc/huc enabling by default" patch
but I couldn't find it and this one seemed similar.


> > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> > Cc: Daniele Ceralo Spurio <daniele.ceraolospurio at intel.com>
> > Cc: Stuart Summers <stuart.summers at intel.com>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Tested-by: Tomas Janousek <tomi at nomi.cz>
> > Signed-off-by: Don Hiatt <don.hiatt at intel.com>
> > ---
> >   drivers/gpu/drm/i915/gt/uc/intel_guc.c | 7 +++++++
> >   drivers/gpu/drm/i915/gt/uc/intel_uc.c  | 8 ++++++++
> >   drivers/gpu/drm/i915/i915_drv.h        | 6 ++++++
> >   3 files changed, 21 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > index 019ae6486e8d..92d9305c0d73 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > @@ -553,6 +553,13 @@ int intel_guc_suspend(struct intel_guc *guc)
> >   		GUC_POWER_D1, /* any value greater than GUC_POWER_D0
> */
> >   	};
> >
> > +	/*
> > +	 * If GuC communication is enabled but submission is not supported,
> > +	 * we do not need to suspend the GuC.
> > +	 */
> > +	if (!intel_guc_submission_is_enabled(guc))
> > +		return 0;
> > +
> >   	/*
> >   	 * The ENTER_S_STATE action queues the save/restore operation in GuC
> FW
> >   	 * and then returns, so waiting on the H2G is not enough to guarantee
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > index 629b19377a29..4dd43b99a334 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
> > @@ -605,6 +605,14 @@ static int __uc_resume(struct intel_uc *uc, bool
> enable_communication)
> >   	if (enable_communication)
> >   		guc_enable_communication(guc);
> >
> > +	/*
> > +	 * If GuC communication is enabled but submission is not supported,
> > +	 * we do not need to resume the GuC but we do need to enable the
> > +	 * GuC communication on resume (above).
> > +	 */
> > +	if (!intel_guc_submission_is_enabled(guc))
> > +		return 0;
> > +
> 
> I would put this check inside intel_guc_resume(), for symmetry with the
> one you put inside intel_guc_suspend().
> 

Will do.

> Daniele
> 
> >   	err = intel_guc_resume(guc);
> >   	if (err) {
> >   		DRM_DEBUG_DRIVER("Failed to resume GuC, err=%d", err);
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> b/drivers/gpu/drm/i915/i915_drv.h
> > index 7bc1d8c102b2..2b879472e760 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -2044,4 +2044,10 @@ i915_coherent_map_type(struct drm_i915_private
> *i915)
> >   	return HAS_LLC(i915) ? I915_MAP_WB : I915_MAP_WC;
> >   }
> >
> > +static inline bool intel_guc_submission_is_enabled(struct intel_guc *guc)
> > +{
> > +	return intel_guc_is_submission_supported(guc) &&
> > +		intel_guc_is_running(guc);
> > +}
> > +
> >   #endif
> >