Re: [PATCH v2 4.1/10] drm/i915: get a permanent RPM reference on platforms w/o RPM support

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

On ke, 2015-12-16 at 19:26 +0200, Ville Syrjälä wrote:
> On Wed, Dec 16, 2015 at 03:53:32PM +0200, Imre Deak wrote:
> > Currently we get a permanent RPM reference if the platform doesn't
> > support RPM, but this is implicit via the dependency of the power
> > well
> > functionality on RPM the RPM support, see
> > sanitize_disable_power_well_option(). Make things more explicit by
> > taking an RPM reference only for the purpose of keeping RPM
> > disabled.
> > This provides better documentation and safety against future
> > changes
> > that would break the above dependency.
> > 
> > v2:
> > - fix intel_runtime_pm_get vs. intel_runtime_pm_put in
> >   intel_power_domains_fini()
> > 
> > Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> 
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> > ---
> >  drivers/gpu/drm/i915/intel_runtime_pm.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c
> > b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > index cee54ea..c35f12c 100644
> > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > @@ -1992,6 +1992,13 @@ void intel_power_domains_fini(struct
> > drm_i915_private *dev_priv)
> >  	/* Remove the refcount we took to keep power well support
> > disabled. */
> >  	if (!i915.disable_power_well)
> >  		intel_display_power_put(dev_priv,
> > POWER_DOMAIN_INIT);
> > +
> > +	/*
> > +	 * Remove the refcount we took in
> > intel_runtime_pm_enable() in case
> > +	 * the platform doesn't support runtime PM.
> > +	 */
> > +	if (!HAS_RUNTIME_PM(dev_priv))
> > +		intel_runtime_pm_put(dev_priv);

Ville noticed another issue here, with this we wouldn't have RPM ref
tracking coverage on old platforms. We can solve this by using the low
level pm_runtime_put()/pm_runtime_get_sync() for this instead, will
send a v3 with this changed.

> >  }
> >  
> >  static void intel_power_domains_sync_hw(struct drm_i915_private
> > *dev_priv)
> > @@ -2305,6 +2312,9 @@ void intel_runtime_pm_enable(struct
> > drm_i915_private *dev_priv)
> >  	struct drm_device *dev = dev_priv->dev;
> >  	struct device *device = &dev->pdev->dev;
> >  
> > +	if (!HAS_RUNTIME_PM(dev_priv))
> > +		intel_runtime_pm_get(dev_priv);
> > +
> >  	pm_runtime_set_autosuspend_delay(device, 10000); /* 10s */
> >  	pm_runtime_mark_last_busy(device);
> >  	pm_runtime_use_autosuspend(device);
> > -- 
> > 2.5.0
> 
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