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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: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: stable@kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Chris Wilson 2012-05-09 21:45:43 +01:00 committed by Daniel Vetter
parent 59de3295ad
commit 9adab8b5a7
1 changed files with 3 additions and 6 deletions
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9
drivers/gpu/drm/i915/i915_irq.c
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@ -533,14 +533,11 @@ out:
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) {