[Intel-gfx] [PATCH 02/10] drm/i915: disable power well support on platforms without runtime PM support

[Imre Deak]

On Tue, 2015-12-15 at 22:57 +0200, Ville Syrjälä wrote:
> On Tue, Dec 15, 2015 at 08:10:30PM +0200, Imre Deak wrote:
> > All platforms with power well support have runtime PM support, so
> > simplify things by explicitly disabling power well support on
> > platforms
> > without runtime PM support. This results in holding the init power
> > domain
> > reference whenever the driver is loaded in addition to an RPM
> > reference,
> > which reflects the reality better and makes it possible to simplify
> > things by removing the HAS_RUNTIME_PM special casing from more
> > places in
> > a follow-up patch.
> > 
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_runtime_pm.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c
> > b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > index 9945040..f4ff5f5 100644
> > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > @@ -1908,6 +1908,11 @@ static int
> >  sanitize_disable_power_well_option(const struct drm_i915_private
> > *dev_priv,
> >  				   int disable_power_well)
> >  {
> > +	if (!HAS_RUNTIME_PM(dev_priv)) {
> > +		DRM_DEBUG_KMS("No runtime PM support, disabling
> > display power well support\n");
> > +		return 0;
> > +	}
> 
> Feels a bit too magic to me. Needs a comment at least, otherwise
> someone
> is going to change disable_power_well back into something you can
> disable
> at runtime and then all the old stuff might break.
> 
> Grabbing an extra rpm reference explicitly for this purpose might be
> less confusing.

Ok, agreed. But making power well support depend on RPM still ok with
you? I can add then the extra RPM get/put only for !HAS_RUNTIME_PM.

> 
> > +
> >  	if (disable_power_well >= 0)
> >  		return !!disable_power_well;
> >  
> > -- 
> > 2.5.0
>