Messages in this thread Patch in this message | | | Date | Mon, 28 May 2012 04:13:34 +0100 | From | Ben Hutchings <> | Subject | [ 092/117] drm/i915: Avoid a double-read of PCH_IIR during interrupt handling |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: Chris Wilson <chris@chris-wilson.co.uk>
commit 9adab8b5a7fde248504f484e197589f3e3c922e2 upstream.
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> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/gpu/drm/i915/i915_irq.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)
--- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -424,14 +424,11 @@ mutex_unlock(&dev_priv->dev->struct_mutex); } -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) >> @@ -529,7 +526,7 @@ 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) { @@ -629,7 +626,7 @@ 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) {
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