From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120527002620.340721575@linuxfoundation.org> Date: Sun, 27 May 2012 09:26:56 +0900 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Chris Wilson , Jesse Barnes , Daniel Vetter Subject: [ 43/55] drm/i915: Avoid a double-read of PCH_IIR during interrupt handling In-Reply-To: <20120527005203.GA2146@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Wilson 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 Cc: Jesse Barnes Signed-off-by: Daniel Vetter Signed-off-by: Greg Kroah-Hartman --- 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 @@ -422,14 +422,11 @@ static void gen6_pm_rps_work(struct work 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) >> @@ -527,7 +524,7 @@ static irqreturn_t ivybridge_irq_handler 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) { @@ -626,7 +623,7 @@ static irqreturn_t ironlake_irq_handler( 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) {