[PATCH] drm/i915: vlv: init only needed state during early power well enabling

[PATCH] drm/i915: vlv: init only needed state during early power well enabling

[Imre Deak]

During the initial power well enabling on the driver init/resume path
we can avoid initialzing part of the HW/SW state that will be
initialized anyway by the subsequent init/resume code. For some steps
like HPD initialization this redundancy is not only an overhead but an
actual problem, since they can't be run this early in the overall init
sequence.

Add a flag marking the init phase and skip reinitialzing state that is
not strictly necessary based on that.

This is also needed by the upcoming HPD init restructuring by Thierry
and Daniel.

Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h |  1 +
 drivers/gpu/drm/i915/intel_pm.c | 14 ++++++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7d6acb4..b589fc0 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -929,6 +929,7 @@ struct i915_power_domains {
 	 * time are on. They are kept on until after the first modeset.
 	 */
 	bool init_power_on;
+	bool initializing;
 	int power_well_count;
 
 	struct mutex lock;
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 75c1c76..34b689f 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5622,11 +5622,13 @@ static void vlv_display_power_well_enable(struct drm_i915_private *dev_priv,
 	spin_unlock_irq(&dev_priv->irq_lock);
 
 	/*
-	 * During driver initialization we need to defer enabling hotplug
-	 * processing until fbdev is set up.
+	 * During driver initialization/resume we can avoid restoring the
+	 * part of the HW/SW state that will be inited anyway explicitly.
 	 */
-	if (dev_priv->enable_hotplug_processing)
-		intel_hpd_init(dev_priv->dev);
+	if (dev_priv->power_domains.initializing)
+		return;
+
+	intel_hpd_init(dev_priv->dev);
 
 	i915_redisable_vga_power_on(dev_priv->dev);
 }
@@ -5990,9 +5992,13 @@ static void intel_power_domains_resume(struct drm_i915_private *dev_priv)
 
 void intel_power_domains_init_hw(struct drm_i915_private *dev_priv)
 {
+	struct i915_power_domains *power_domains = &dev_priv->power_domains;
+
+	power_domains->initializing = true;
 	/* For now, we need the power well to be always enabled. */
 	intel_display_set_init_power(dev_priv, true);
 	intel_power_domains_resume(dev_priv);
+	power_domains->initializing = false;
 }
 
 void intel_aux_display_runtime_get(struct drm_i915_private *dev_priv)
-- 
1.8.4

Re: [PATCH] drm/i915: vlv: init only needed state during early power well enabling

[Daniel Vetter]

On Fri, Apr 25, 2014 at 01:19:05PM +0300, Imre Deak wrote:
> During the initial power well enabling on the driver init/resume path
> we can avoid initialzing part of the HW/SW state that will be
> initialized anyway by the subsequent init/resume code. For some steps
> like HPD initialization this redundancy is not only an overhead but an
> actual problem, since they can't be run this early in the overall init
> sequence.
> 
> Add a flag marking the init phase and skip reinitialzing state that is
> not strictly necessary based on that.
> 
> This is also needed by the upcoming HPD init restructuring by Thierry
> and Daniel.
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>

Not too happy with the layering violation. But we've discussed this
extensively on irc, and there doesn't seem to be anything less ugly
available.

Queued for -next, thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_drv.h |  1 +
>  drivers/gpu/drm/i915/intel_pm.c | 14 ++++++++++----
>  2 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 7d6acb4..b589fc0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -929,6 +929,7 @@ struct i915_power_domains {
>  	 * time are on. They are kept on until after the first modeset.
>  	 */
>  	bool init_power_on;
> +	bool initializing;
>  	int power_well_count;
>  
>  	struct mutex lock;
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 75c1c76..34b689f 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5622,11 +5622,13 @@ static void vlv_display_power_well_enable(struct drm_i915_private *dev_priv,
>  	spin_unlock_irq(&dev_priv->irq_lock);
>  
>  	/*
> -	 * During driver initialization we need to defer enabling hotplug
> -	 * processing until fbdev is set up.
> +	 * During driver initialization/resume we can avoid restoring the
> +	 * part of the HW/SW state that will be inited anyway explicitly.
>  	 */
> -	if (dev_priv->enable_hotplug_processing)
> -		intel_hpd_init(dev_priv->dev);
> +	if (dev_priv->power_domains.initializing)
> +		return;
> +
> +	intel_hpd_init(dev_priv->dev);
>  
>  	i915_redisable_vga_power_on(dev_priv->dev);
>  }
> @@ -5990,9 +5992,13 @@ static void intel_power_domains_resume(struct drm_i915_private *dev_priv)
>  
>  void intel_power_domains_init_hw(struct drm_i915_private *dev_priv)
>  {
> +	struct i915_power_domains *power_domains = &dev_priv->power_domains;
> +
> +	power_domains->initializing = true;
>  	/* For now, we need the power well to be always enabled. */
>  	intel_display_set_init_power(dev_priv, true);
>  	intel_power_domains_resume(dev_priv);
> +	power_domains->initializing = false;
>  }
>  
>  void intel_aux_display_runtime_get(struct drm_i915_private *dev_priv)
> -- 
> 1.8.4
> 
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch