[Intel-gfx] [RFC] drm/i915: Disable connector polling at runtime suspend

[Anshuman Gupta]

On 2020-07-21 at 16:32:17 +0300, Imre Deak wrote:
> On Fri, Jul 17, 2020 at 05:34:25PM +0530, Anshuman Gupta wrote:
> > While i915 device is in runtime suspend, DRM connector polling
> > causing device to wakeup from runtime suspend.
> > This harm overall cpu idle statistics, therefore
> > disabling polling while in runtime suspend.
> 
> Before disabling polling we would need to enable hotplug interrupts
> during the runtime suspended state. Also I haven't seen yet stats where
IMHO whilst it is deepest display C state, HOTPLUG interrupt will be
disabled.
> polling (which has a 10 sec period) have a significant effect on
> idle residencies.
IMHO it can still affect the runtime s0ix.

Thanks,
Anshuman Gupta.

> 
> > Cc: Imre Deak <imre.deak at intel.com>
> > Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> > index 5fd5af4bc855..1229c72f19c9 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -1595,6 +1595,8 @@ static int intel_runtime_suspend(struct device *kdev)
> >  
> >  	disable_rpm_wakeref_asserts(rpm);
> >  
> > +	drm_kms_helper_poll_disable(&dev_priv->drm);
> > +
> >  	/*
> >  	 * We are safe here against re-faults, since the fault handler takes
> >  	 * an RPM reference.
> > @@ -1699,6 +1701,8 @@ static int intel_runtime_resume(struct device *kdev)
> >  	 */
> >  	intel_gt_runtime_resume(&dev_priv->gt);
> >  
> > +	drm_kms_helper_poll_enable(&dev_priv->drm);
> > +
> >  	/*
> >  	 * On VLV/CHV display interrupts are part of the display
> >  	 * power well, so hpd is reinitialized from there. For
> > -- 
> > 2.26.2
> >