[Intel-gfx] [PATCH] drm/i915: HSW: allow PCH clock gating for suspend

[Imre Deak]

On Tue, 2013-04-16 at 14:50 -0300, Paulo Zanoni wrote:
> 2013/4/16 Imre Deak <imre.deak at intel.com>:
> > On Tue, 2013-04-16 at 14:35 +0300, Ville Syrjälä wrote:
> >> On Tue, Apr 16, 2013 at 02:25:16PM +0300, Imre Deak wrote:
> >> > For the device to enter D3 we should enable PCH clock gating.
> >> >
> >> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> >> > ---
> >> >  drivers/gpu/drm/i915/i915_drv.c      |    2 ++
> >> >  drivers/gpu/drm/i915/i915_drv.h      |    1 +
> >> >  drivers/gpu/drm/i915/intel_display.c |    5 +++++
> >> >  drivers/gpu/drm/i915/intel_drv.h     |    1 +
> >> >  drivers/gpu/drm/i915/intel_pm.c      |   18 ++++++++++++++++++
> >> >  5 files changed, 27 insertions(+)
> >> >
> >> > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> >> > index bddb9a5..e9a82f1 100644
> >> > --- a/drivers/gpu/drm/i915/i915_drv.c
> >> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> >> > @@ -521,6 +521,8 @@ static int i915_drm_freeze(struct drm_device *dev)
> >> >              */
> >> >             list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
> >> >                     dev_priv->display.crtc_disable(crtc);
> >> > +
> >> > +           intel_modeset_suspend_hw(dev);
> >> >     }
> >> >
> >> >     i915_save_state(dev);
> >> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> >> > index b5a495a..e549e6c 100644
> >> > --- a/drivers/gpu/drm/i915/i915_drv.h
> >> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> >> > @@ -1831,6 +1831,7 @@ static inline void intel_unregister_dsm_handler(void) { return; }
> >> >
> >> >  /* modesetting */
> >> >  extern void intel_modeset_init_hw(struct drm_device *dev);
> >> > +extern void intel_modeset_suspend_hw(struct drm_device *dev);
> >> >  extern void intel_modeset_init(struct drm_device *dev);
> >> >  extern void intel_modeset_gem_init(struct drm_device *dev);
> >> >  extern void intel_modeset_cleanup(struct drm_device *dev);
> >> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> >> > index 457a0a0..e9192bf 100644
> >> > --- a/drivers/gpu/drm/i915/intel_display.c
> >> > +++ b/drivers/gpu/drm/i915/intel_display.c
> >> > @@ -8984,6 +8984,11 @@ void intel_modeset_init_hw(struct drm_device *dev)
> >> >     mutex_unlock(&dev->struct_mutex);
> >> >  }
> >> >
> >> > +void intel_modeset_suspend_hw(struct drm_device *dev)
> >> > +{
> >> > +   intel_suspend_hw(dev);
> >> > +}
> >> > +
> >>
> >> Why this extra level of indirection?
> >
> > I thought it'd be more symmetric w.r.t.
> >
> >  __i915_drm_thaw->intel_modeset_init_hw().
> >
> >> >  void intel_modeset_init(struct drm_device *dev)
> >> >  {
> >> >     struct drm_i915_private *dev_priv = dev->dev_private;
> >> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> >> > index d7bd031..8b29897 100644
> >> > --- a/drivers/gpu/drm/i915/intel_drv.h
> >> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> >> > @@ -652,6 +652,7 @@ extern void assert_pipe(struct drm_i915_private *dev_priv, enum pipe pipe,
> >> >  #define assert_pipe_disabled(d, p) assert_pipe(d, p, false)
> >> >
> >> >  extern void intel_init_clock_gating(struct drm_device *dev);
> >> > +extern void intel_suspend_hw(struct drm_device *dev);
> >> >  extern void intel_write_eld(struct drm_encoder *encoder,
> >> >                         struct drm_display_mode *mode);
> >> >  extern void intel_cpt_verify_modeset(struct drm_device *dev, int pipe);
> >> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> >> > index baea4fc..3567881 100644
> >> > --- a/drivers/gpu/drm/i915/intel_pm.c
> >> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> >> > @@ -3735,6 +3735,18 @@ static void lpt_init_clock_gating(struct drm_device *dev)
> >> >                        PCH_LP_PARTITION_LEVEL_DISABLE);
> >> >  }
> >> >
> >> > +static void lpt_allow_clock_gating(struct drm_device *dev)
> >> > +{
> >> > +   struct drm_i915_private *dev_priv = dev->dev_private;
> >> > +
> >> > +   if (dev_priv->pch_id == INTEL_PCH_LPT_LP_DEVICE_ID_TYPE) {
> >> > +           uint32_t val = I915_READ(SOUTH_DSPCLK_GATE_D);
> >> > +
> >> > +           val &= ~PCH_LP_PARTITION_LEVEL_DISABLE;
> >> > +           I915_WRITE(SOUTH_DSPCLK_GATE_D, val);
> >> > +   }
> >>
> >> So who sets it back when we resume?
> >
> > intel_modeset_init_hw()->intel_init_clock_gating()
> >
> >>
> >> > +}
> >> > +
> >> >  static void haswell_init_clock_gating(struct drm_device *dev)
> >> >  {
> >> >     struct drm_i915_private *dev_priv = dev->dev_private;
> >> > @@ -4085,6 +4097,12 @@ void intel_init_clock_gating(struct drm_device *dev)
> >> >     dev_priv->display.init_clock_gating(dev);
> >> >  }
> >> >
> >> > +void intel_suspend_hw(struct drm_device *dev)
> >> > +{
> >> > +   if (IS_HASWELL(dev))
> >> > +           lpt_allow_clock_gating(dev);
> >>
> >> Do you need the HSW check? Isn't the LPT LP check enough?
> >
> > Not sure. According to the spec this is a workaround for HSW/LPT.
> 
> I'd check for HAS_PCH_LPT before calling lpt_allow_clock_gating. Let's
> not forget that, for example, PPT is considered the same as CPT, so
> any code that's inside a "HAS_PCH_CPT" runs for both SNB and IVB.
> 
> Optional bikeshed: maybe rename "lpt_allow_clock_gating" to "lpt_suspend_hw"?

Ok, will change these.

--Imre