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

[Imre Deak]

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.

> > +}
> > +
> >  void intel_set_power_well(struct drm_device *dev, bool enable)
> >  {
> >  	struct drm_i915_private *dev_priv = dev->dev_private;
> > -- 
> > 1.7.10.4
> > 
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>