Re: [PATCH 6/6] drm/i915: drop locking from asle pipestat enable

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Apr 29, 2013 at 01:02:55PM +0300, Jani Nikula wrote:
> Enable asle pipestat earlier in i915/i965 irq postinstall to not need
> irq_lock in i915_enable_asle_pipestat().
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Honestly I'm not too fond of too clever init sequence ordering - we
already get the inherent constraints of the setup sequence wrong way too
often. Trying to avoid a spinlock at setup time with clever ordering feels
like the wrong tradeoff here.

So I'd prefer a WARN(!spin_is_locked) instead in enable_pipestat (plus
lock grabbing in the vlv/i965 postinstall code).

All other patches from this series merged, thanks.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_irq.c |   12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 03a31be..0243db1 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -354,18 +354,13 @@ i915_disable_pipestat(drm_i915_private_t *dev_priv, int pipe, u32 mask)
>  static void i915_enable_asle_pipestat(struct drm_device *dev)
>  {
>  	drm_i915_private_t *dev_priv = dev->dev_private;
> -	unsigned long irqflags;
>  
>  	if (!dev_priv->opregion.asle || !IS_MOBILE(dev))
>  		return;
>  
> -	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
> -
>  	i915_enable_pipestat(dev_priv, 1, PIPE_LEGACY_BLC_EVENT_ENABLE);
>  	if (INTEL_INFO(dev)->gen >= 4)
>  		i915_enable_pipestat(dev_priv, 0, PIPE_LEGACY_BLC_EVENT_ENABLE);
> -
> -	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
>  }
>  
>  /**
> @@ -2953,6 +2948,8 @@ static int i915_irq_postinstall(struct drm_device *dev)
>  		I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT |
>  		I915_USER_INTERRUPT;
>  
> +	i915_enable_asle_pipestat(dev);
> +
>  	if (I915_HAS_HOTPLUG(dev)) {
>  		I915_WRITE(PORT_HOTPLUG_EN, 0);
>  		POSTING_READ(PORT_HOTPLUG_EN);
> @@ -2967,8 +2964,6 @@ static int i915_irq_postinstall(struct drm_device *dev)
>  	I915_WRITE(IER, enable_mask);
>  	POSTING_READ(IER);
>  
> -	i915_enable_asle_pipestat(dev);
> -
>  	return 0;
>  }
>  
> @@ -3178,6 +3173,7 @@ static int i965_irq_postinstall(struct drm_device *dev)
>  		enable_mask |= I915_BSD_USER_INTERRUPT;
>  
>  	i915_enable_pipestat(dev_priv, 0, PIPE_GMBUS_EVENT_ENABLE);
> +	i915_enable_asle_pipestat(dev);
>  
>  	/*
>  	 * Enable some error detection, note the instruction error mask
> @@ -3201,8 +3197,6 @@ static int i965_irq_postinstall(struct drm_device *dev)
>  	I915_WRITE(PORT_HOTPLUG_EN, 0);
>  	POSTING_READ(PORT_HOTPLUG_EN);
>  
> -	i915_enable_asle_pipestat(dev);
> -
>  	return 0;
>  }
>  
> -- 
> 1.7.9.5
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch