Re: [PATCH] drm/i915: HSW: allow PCH clock gating for suspend

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

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@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?

>  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?

> +}
> +
>  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?

> +}
> +
>  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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-- 
Ville Syrjälä
Intel OTC