Re: [PATCH 1/2] drm/i915: Make sure pipe interrupts are processed before turning off power well on BDW+

[Imre Deak <imre.deak@intel.com>]

On pe, 2016-02-19 at 20:47 +0200, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Starting from BDW the DE_PIPE interrupts for pipe B and C belong to the
> relevant display power well. So we should make sure we've finished
> processing them before turning off the power well.
> 
> The pipe interrupts shouldn't really happen at this point anymore since
> we've already shut down the planes/pipes/whatnot, but being a bit
> paranoid shouldn't hurt.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c         | 16 ++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h        |  2 ++
>  drivers/gpu/drm/i915/intel_runtime_pm.c | 19 +++++++++++++++++++
>  3 files changed, 37 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index d56c261ad867..a9048e1b96e5 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -3366,6 +3366,22 @@ void gen8_irq_power_well_post_enable(struct drm_i915_private *dev_priv,
>  	spin_unlock_irq(&dev_priv->irq_lock);
>  }
>  
> +void gen8_irq_power_well_pre_disable(struct drm_i915_private *dev_priv,
> +				     unsigned int pipe_mask)
> +{
> +	spin_lock_irq(&dev_priv->irq_lock);
> +	if (pipe_mask & 1 << PIPE_A)
> +		GEN8_IRQ_RESET_NDX(DE_PIPE, PIPE_A);
> +	if (pipe_mask & 1 << PIPE_B)
> +		GEN8_IRQ_RESET_NDX(DE_PIPE, PIPE_B);
> +	if (pipe_mask & 1 << PIPE_C)
> +		GEN8_IRQ_RESET_NDX(DE_PIPE, PIPE_C);
> +	spin_unlock_irq(&dev_priv->irq_lock);
> +
> +	/* make sure we're done processing display irqs */
> +	synchronize_irq(dev_priv->dev->irq);
> +}
> +
>  static void cherryview_irq_preinstall(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 285b0570be9c..2618e3026e8b 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -993,6 +993,8 @@ static inline bool intel_irqs_enabled(struct drm_i915_private *dev_priv)
>  int intel_get_crtc_scanline(struct intel_crtc *crtc);
>  void gen8_irq_power_well_post_enable(struct drm_i915_private *dev_priv,
>  				     unsigned int pipe_mask);
> +void gen8_irq_power_well_pre_disable(struct drm_i915_private *dev_priv,
> +				     unsigned int pipe_mask);
>  
>  /* intel_crt.c */
>  void intel_crt_init(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index 59e9222223c9..1afa00855ed8 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -284,6 +284,13 @@ static void hsw_power_well_post_enable(struct drm_i915_private *dev_priv)
>  						1 << PIPE_C | 1 << PIPE_B);
>  }
>  
> +static void hsw_power_well_pre_disable(struct drm_i915_private *dev_priv)
> +{
> +	if (IS_BROADWELL(dev_priv))
> +		gen8_irq_power_well_pre_disable(dev_priv,
> +						1 << PIPE_C | 1 << PIPE_B);
> +}
> +
>  static void skl_power_well_post_enable(struct drm_i915_private *dev_priv,
>  				       struct i915_power_well *power_well)
>  {
> @@ -309,6 +316,14 @@ static void skl_power_well_post_enable(struct drm_i915_private *dev_priv,
>  	}
>  }
>  
> +static void skl_power_well_pre_disable(struct drm_i915_private *dev_priv,
> +				       struct i915_power_well *power_well)
> +{
> +	if (power_well->data == SKL_DISP_PW_2)
> +		gen8_irq_power_well_pre_disable(dev_priv,
> +						1 << PIPE_C | 1 << PIPE_B);
> +}
> +
>  static void hsw_set_power_well(struct drm_i915_private *dev_priv,
>  			       struct i915_power_well *power_well, bool enable)
>  {
> @@ -334,6 +349,7 @@ static void hsw_set_power_well(struct drm_i915_private *dev_priv,
>  
>  	} else {
>  		if (enable_requested) {
> +			hsw_power_well_pre_disable(dev_priv);
>  			I915_WRITE(HSW_PWR_WELL_DRIVER, 0);
>  			POSTING_READ(HSW_PWR_WELL_DRIVER);
>  			DRM_DEBUG_KMS("Requesting to disable the power well\n");
> @@ -663,6 +679,9 @@ static void skl_set_power_well(struct drm_i915_private *dev_priv,
>  	state_mask = SKL_POWER_WELL_STATE(power_well->data);
>  	is_enabled = tmp & state_mask;
>  
> +	if (!enable && enable_requested)
> +		skl_power_well_pre_disable(dev_priv, power_well);
> +

Why not putting this in the existing if branch? Either way:
Reviewed-by: Imre Deak <imre.deak@intel.com>

>  	if (enable) {
>  		if (!enable_requested) {
>  			WARN((tmp & state_mask) &&
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