[Intel-gfx] [PATCH 6/9] drm/i915: don't disable/reenable IVB error interrupts when not needed

[Daniel Vetter]

On Tue, Aug 06, 2013 at 06:57:16PM -0300, Paulo Zanoni wrote:
> From: Paulo Zanoni <paulo.r.zanoni at intel.com>
> 
> If the error interrupts are already disabled, don't disable and
> reenable them. This is going to be needed when we're in PC8+, where
> all the interrupts are disabled so we won't risk re-enabling
> DE_ERR_INT_IVB.
> 
> v2: Use dev_priv->irq_mask (Chris)
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index d96bd1b..5e7e6f6 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1373,6 +1373,7 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg)
>  	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
>  	u32 de_iir, gt_iir, de_ier, sde_ier = 0;
>  	irqreturn_t ret = IRQ_NONE;
> +	bool err_int_reenable = false;
>  
>  	atomic_inc(&dev_priv->irq_received);
>  
> @@ -1401,7 +1402,9 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg)
>  	 * handler. */
>  	if (IS_HASWELL(dev)) {
>  		spin_lock(&dev_priv->irq_lock);
> -		ironlake_disable_display_irq(dev_priv, DE_ERR_INT_IVB);
> +		err_int_reenable = ~dev_priv->irq_mask & DE_ERR_INT_IVB;
> +		if (err_int_reenable)
> +			ironlake_disable_display_irq(dev_priv, DE_ERR_INT_IVB);

Hm, that reminds me that this entire logic here is racy wrt concurrent
interrupt enabling on a different cpu core (e.g. due to a modeset now
again allowing display error interrupts). Do we still need this or could
we just ditch this entire complexity?

Maybe I'm just engaging in wishful thinking here a bit ;-)

Patch applied.
-Daniel

>  		spin_unlock(&dev_priv->irq_lock);
>  	}
>  
> @@ -1437,7 +1440,7 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg)
>  		}
>  	}
>  
> -	if (IS_HASWELL(dev)) {
> +	if (err_int_reenable) {
>  		spin_lock(&dev_priv->irq_lock);
>  		if (ivb_can_enable_err_int(dev))
>  			ironlake_enable_display_irq(dev_priv, DE_ERR_INT_IVB);
> -- 
> 1.8.1.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch