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Commit 9adab8b5 authored by Chris Wilson's avatar Chris Wilson Committed by Daniel Vetter
Browse files

drm/i915: Avoid a double-read of PCH_IIR during interrupt handling 



Currently the code re-reads PCH_IIR during the hotplug interrupt
processing. Not only is this a wasted read, but introduces a potential
for handling a spurious interrupt as we then may not clear all the
interrupts processed (since the re-read IIR may contains more interrupts
asserted than we clear using the result of the original read).

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: stable@kernel.org
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 59de3295

drivers/gpu/drm/i915/i915_irq.c

+3 −6
Original line number Diff line number Diff line
@@ -533,14 +533,11 @@ static irqreturn_t valleyview_irq_handler(DRM_IRQ_ARGS) 
	return ret;

}



static void pch_irq_handler(struct drm_device *dev)

static void pch_irq_handler(struct drm_device *dev, u32 pch_iir)

{

	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;

	u32 pch_iir;

	int pipe;



	pch_iir = I915_READ(SDEIIR);



	if (pch_iir & SDE_AUDIO_POWER_MASK)

		DRM_DEBUG_DRIVER("PCH audio power change on port %d\n",

				 (pch_iir & SDE_AUDIO_POWER_MASK) >>
@@ -633,7 +630,7 @@ static irqreturn_t ivybridge_irq_handler(DRM_IRQ_ARGS) 
	if (de_iir & DE_PCH_EVENT_IVB) {

		if (pch_iir & SDE_HOTPLUG_MASK_CPT)

			queue_work(dev_priv->wq, &dev_priv->hotplug_work);

		pch_irq_handler(dev);

		pch_irq_handler(dev, pch_iir);

	}



	if (pm_iir & GEN6_PM_DEFERRED_EVENTS)
@@ -721,7 +718,7 @@ static irqreturn_t ironlake_irq_handler(DRM_IRQ_ARGS) 
	if (de_iir & DE_PCH_EVENT) {

		if (pch_iir & hotplug_mask)

			queue_work(dev_priv->wq, &dev_priv->hotplug_work);

		pch_irq_handler(dev);

		pch_irq_handler(dev, pch_iir);

	}



	if (de_iir & DE_PCU_EVENT) {