[ 092/117] drm/i915: Avoid a double-read of PCH_IIR during interrupt handling
From: Ben Hutchings <hidden>
Date: 2012-05-28 03:36:22
Also in:
lkml
3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Wilson <redacted> 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 <redacted> Cc: Jesse Barnes <redacted> Signed-off-by: Daniel Vetter <redacted> Signed-off-by: Ben Hutchings <redacted> --- 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) {