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

[Paulo Zanoni]

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"?

>
>> > +}
>> > +
>> >  void intel_set_power_well(struct drm_device *dev, bool enable)
>> >  {
>> >     struct drm_i915_private *dev_priv = dev->dev_private;
>> > --
>> > 1.7.10.4
>> >
>> > _______________________________________________
>> > Intel-gfx mailing list
>> > Intel-gfx at lists.freedesktop.org
>> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>
>
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--
Paulo Zanoni