Re: [PATCH v2 08/25] drm/i915: get a runtime PM ref for the deferred GT powersave enabling

Daniel Vetter
2014-04-25T09:09:44Z

On Fri, Apr 25, 2014 at 11:14:26AM +0300, Imre Deak wrote:
> On Fri, 2014-04-25 at 09:59 +0200, Daniel Vetter wrote:
> > On Mon, Apr 14, 2014 at 08:24:29PM +0300, Imre Deak wrote:
> > > At least on VLV but probably on other platforms too we depend on RC6
> > > being enabled for RPM, so disable RPM until the delayed RC6 enabling
> > > completes.
> > >
> > > v2:
> > > - explain the reason for the _noresume version of RPM get (Daniel)
> > > - use the simpler 'if (schedule_work()) rpm_get();' instead of
> > > 'if (!cancel_work_sync()) rpm_get(); schedule_work();'
> > >
> > > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > > ---
> > > drivers/gpu/drm/i915/i915_drv.c | 5 ++++-
> > > drivers/gpu/drm/i915/intel_drv.h | 2 ++
> > > drivers/gpu/drm/i915/intel_pm.c | 34 ++++++++++++++++++++++++++++++++--
> > > 3 files changed, 38 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> > > index a821608..a20d2d1 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.c
> > > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > > @@ -754,7 +754,7 @@ int i915_reset(struct drm_device *dev)
> > > * previous concerns that it doesn't respond well to some forms
> > > * of re-init after reset. */
> > > if (INTEL_INFO(dev)->gen > 5)
> > > - intel_enable_gt_powersave(dev);
> > > + intel_reset_gt_powersave(dev);
> > >
> > > intel_hpd_init(dev);
> > > } else {
> > > @@ -923,6 +923,9 @@ static int intel_runtime_suspend(struct device *device)
> > > struct drm_device *dev = pci_get_drvdata(pdev);
> > > struct drm_i915_private *dev_priv = dev->dev_private;
> > >
> > > + if (WARN_ON_ONCE(!dev_priv->rps.enabled))
> > > + return -ENODEV;
> > > +
> > > WARN_ON(!HAS_RUNTIME_PM(dev));
> > > assert_force_wake_inactive(dev_priv);
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > > index c551472..618d05a 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -924,6 +924,7 @@ void intel_init_gt_powersave(struct drm_device *dev);
> > > void intel_cleanup_gt_powersave(struct drm_device *dev);
> > > void intel_enable_gt_powersave(struct drm_device *dev);
> > > void intel_disable_gt_powersave(struct drm_device *dev);
> > > +void intel_reset_gt_powersave(struct drm_device *dev);
> > > void ironlake_teardown_rc6(struct drm_device *dev);
> > > void gen6_update_ring_freq(struct drm_device *dev);
> > > void gen6_rps_idle(struct drm_i915_private *dev_priv);
> > > @@ -931,6 +932,7 @@ void gen6_rps_boost(struct drm_i915_private *dev_priv);
> > > void intel_aux_display_runtime_get(struct drm_i915_private *dev_priv);
> > > void intel_aux_display_runtime_put(struct drm_i915_private *dev_priv);
> > > void intel_runtime_pm_get(struct drm_i915_private *dev_priv);
> > > +void intel_runtime_pm_get_noresume(struct drm_i915_private *dev_priv);
> > > void intel_runtime_pm_put(struct drm_i915_private *dev_priv);
> > > void intel_init_runtime_pm(struct drm_i915_private *dev_priv);
> > > void intel_fini_runtime_pm(struct drm_i915_private *dev_priv);
> > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > > index e5b9f08..0e8b263 100644
> > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > @@ -4549,6 +4549,8 @@ static void intel_gen6_powersave_work(struct work_struct *work)
> > > }
> > > dev_priv->rps.enabled = true;
> > > mutex_unlock(&dev_priv->rps.hw_lock);
> > > +
> > > + intel_runtime_pm_put(dev_priv);
> > > }
> > >
> > > void intel_enable_gt_powersave(struct drm_device *dev)
> > > @@ -4566,12 +4568,28 @@ void intel_enable_gt_powersave(struct drm_device *dev)
> > > * PCU communication is slow and this doesn't need to be
> > > * done at any specific time, so do this out of our fast path
> > > * to make resume and init faster.
> > > + *
> > > + * We depend on the HW RC6 power context save/restore
> > > + * mechanism when entering D3 through runtime PM suspend. So
> > > + * disable RPM until RPS/RC6 is properly setup. We can only
> > > + * get here via the driver load/system resume/runtime resume
> > > + * paths, so the _noresume version is enough (and in case of
> > > + * runtime resume it's necessary).
> > > */
> > > - schedule_delayed_work(&dev_priv->rps.delayed_resume_work,
> > > - round_jiffies_up_relative(HZ));
> > > + if (schedule_delayed_work(&dev_priv->rps.delayed_resume_work,
> > > + round_jiffies_up_relative(HZ)))
> > > + intel_runtime_pm_get_noresume(dev_priv);
> > > }
> > > }
> > >
> > > +void intel_reset_gt_powersave(struct drm_device *dev)
> > > +{
> > > + struct drm_i915_private *dev_priv = dev->dev_private;
> > > +
> > > + dev_priv->rps.enabled = false;
> > > + intel_enable_gt_powersave(dev);
> > > +}
> > > +
> > > static void ibx_init_clock_gating(struct drm_device *dev)
> > > {
> > > struct drm_i915_private *dev_priv = dev->dev_private;
> > > @@ -6025,6 +6043,18 @@ void intel_runtime_pm_get(struct drm_i915_private *dev_priv)
> > > WARN(dev_priv->pm.suspended, "Device still suspended.\n");
> > > }
> > >
> > > +void intel_runtime_pm_get_noresume(struct drm_i915_private *dev_priv)
> > > +{
> > > + struct drm_device *dev = dev_priv->dev;
> > > + struct device *device = &dev->pdev->dev;
> > > +
> > > + if (!HAS_RUNTIME_PM(dev))
> > > + return;
> > > +
> > > + WARN(dev_priv->pm.suspended, "Getting nosync-ref while suspended.\n");
> >
> > Do we really need our own tracking in dev_priv->pm.suspended, is there
> > nothing in the runtime pm core which we could use instaed?
>
> Hm, yes by a quick look pm_runtime_suspended() seems like what we could
> use instead. But this was just copy&paste, and the rest of the spots
> would need changing too, so could we do it as a follow-up?

Sure, and then we could remove them all. Was just something I've spotted
since in general I don't like it if we track the same state in multiple
places - sooner or later it will get out of sync and lead to subtile bugs.

dev_priv->pm.irqs_enabled is also a bit a tricky bit since we already have
dev->irqs_enable. But they do track something slightly different, so we
need to keep that one. Still confusing at first glance.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch