Re: [PATCH] drm/i915: Use chipset-specific irq installers

[Ben Widawsky <ben@bwidawsk.net>]

On Tue, Jun 28, 2011 at 11:48:51AM +0100, Chris Wilson wrote:
> Konstantin Belousov pointed out that 4697995b98417 replaced the generic
> i915_driver_irq_*install() functions with chipset specific routines
> accessible only through driver->irq_*install(). So update the sanity
> check in i915_request_wait() to match.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_gem.c |   31 ++++++++++++++++++++-----------
>  1 files changed, 20 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 60268173..add0141 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2029,6 +2029,25 @@ i915_gem_retire_work_handler(struct work_struct *work)
>  	mutex_unlock(&dev->struct_mutex);
>  }
>  
> +static void assert_irq_enabled(struct intel_ring_buffer *ring)
> +{
> +	struct drm_device *dev = ring->dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	u32 ier;
> +
> +	if (HAS_PCH_SPLIT(dev))
> +		ier = I915_READ(DEIER) | I915_READ(GTIER);
> +	else
> +		ier = I915_READ(IER);
> +
> +	if (!ier) {
> +		DRM_ERROR("something (likely vbetool) disabled "
> +			  "interrupts, re-enabling\n");
> +		dev->driver->irq_preinstall(dev);
> +		dev->driver->irq_postinstall(dev);
> +	}
> +}
> +
>  /**
>   * Waits for a sequence number to be signaled, and cleans up the
>   * request and object lists appropriately for that event.
> @@ -2038,7 +2057,6 @@ i915_wait_request(struct intel_ring_buffer *ring,
>  		  uint32_t seqno)
>  {
>  	drm_i915_private_t *dev_priv = ring->dev->dev_private;
> -	u32 ier;
>  	int ret = 0;
>  
>  	BUG_ON(seqno == 0);
> @@ -2073,16 +2091,7 @@ i915_wait_request(struct intel_ring_buffer *ring,
>  	}
>  
>  	if (!i915_seqno_passed(ring->get_seqno(ring), seqno)) {
> -		if (HAS_PCH_SPLIT(ring->dev))
> -			ier = I915_READ(DEIER) | I915_READ(GTIER);
> -		else
> -			ier = I915_READ(IER);
> -		if (!ier) {
> -			DRM_ERROR("something (likely vbetool) disabled "
> -				  "interrupts, re-enabling\n");
> -			i915_driver_irq_preinstall(ring->dev);
> -			i915_driver_irq_postinstall(ring->dev);
> -		}
> +		assert_irq_enabled(ring);
>  
>  		trace_i915_gem_request_wait_begin(ring, seqno);
>  

I'm not totally thrilled with the name. It would make more sense to me
if you had something like:
if (!is_irq_enabled(ring)) {
	DRM_ERROR(...);
	dev->driver->irq_preinstall(ring->dev);
	dev->driver->irq_postinstall(ring->dev);
}

This allows allows for error checking at other points without changing
state.

I'm very nitpicky when it comes to the work assert :p

Ben