[Intel-gfx] [patch] remove loop in Ironlake intrrupt hander

[Zhenyu Wang]

On 2010.01.14 10:06:24 +0800, Zou, Nanhai wrote:
> On Ironlake, there is an interrupt master control bit.
> With the bit disabled before clearing IIR, we do not need to handle extra interrupt in a loop.
> This patch removes the loop in Ironlake interrupt handler
> It fixed irq lost issue on some Ironlake platforms.
> 

Here's my refreshed one, if no IIR has irq bits on, don't forget
to turn on master irq control in DEIER again, and also with indent
style fix.

Eric, please help to push this urgent fix. Thanks.

From 2950bc0b485dfc3b15810ada437643107a80dda5 Mon Sep 17 00:00:00 2001
From: Zou Nan hai <nanhai.zou at intel.com>
Date: Fri, 15 Jan 2010 09:16:19 +0800
Subject: [PATCH] drm/i915: remove loop in Ironlake interrupt handler

On Ironlake, there is an interrupt master control bit. With the bit
disabled before clearing IIR, we do not need to handle extra interrupt
in a loop. This patch removes the loop in Ironlake interrupt handler.
It fixed irq lost issue on some Ironlake platforms.

Cc: Stable Team <stable at kernel.org>
Signed-off-by: Zou Nan hai <Nanhai.zou at intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c |   68 ++++++++++++++++----------------------
 1 files changed, 29 insertions(+), 39 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 7cd8110..89a071a 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -274,7 +274,6 @@ irqreturn_t ironlake_irq_handler(struct drm_device *dev)
 	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
 	int ret = IRQ_NONE;
 	u32 de_iir, gt_iir, de_ier, pch_iir;
-	u32 new_de_iir, new_gt_iir, new_pch_iir;
 	struct drm_i915_master_private *master_priv;
 
 	/* disable master interrupt before clearing iir  */
@@ -286,51 +285,42 @@ irqreturn_t ironlake_irq_handler(struct drm_device *dev)
 	gt_iir = I915_READ(GTIIR);
 	pch_iir = I915_READ(SDEIIR);
 
-	for (;;) {
-		if (de_iir == 0 && gt_iir == 0 && pch_iir == 0)
-			break;
-
-		ret = IRQ_HANDLED;
+	if (de_iir == 0 && gt_iir == 0 && pch_iir == 0)
+		goto done;
 
-		/* should clear PCH hotplug event before clear CPU irq */
-		I915_WRITE(SDEIIR, pch_iir);
-		new_pch_iir = I915_READ(SDEIIR);
+	ret = IRQ_HANDLED;
 
-		I915_WRITE(DEIIR, de_iir);
-		new_de_iir = I915_READ(DEIIR);
-		I915_WRITE(GTIIR, gt_iir);
-		new_gt_iir = I915_READ(GTIIR);
-
-		if (dev->primary->master) {
-			master_priv = dev->primary->master->driver_priv;
-			if (master_priv->sarea_priv)
-				master_priv->sarea_priv->last_dispatch =
-					READ_BREADCRUMB(dev_priv);
-		}
-
-		if (gt_iir & GT_USER_INTERRUPT) {
-			u32 seqno = i915_get_gem_seqno(dev);
-			dev_priv->mm.irq_gem_seqno = seqno;
-			trace_i915_gem_request_complete(dev, seqno);
-			DRM_WAKEUP(&dev_priv->irq_queue);
-			dev_priv->hangcheck_count = 0;
-			mod_timer(&dev_priv->hangcheck_timer, jiffies + DRM_I915_HANGCHECK_PERIOD);
-		}
+	if (dev->primary->master) {
+		master_priv = dev->primary->master->driver_priv;
+		if (master_priv->sarea_priv)
+			master_priv->sarea_priv->last_dispatch =
+				READ_BREADCRUMB(dev_priv);
+	}
 
-		if (de_iir & DE_GSE)
-			ironlake_opregion_gse_intr(dev);
+	if (gt_iir & GT_USER_INTERRUPT) {
+		u32 seqno = i915_get_gem_seqno(dev);
+		dev_priv->mm.irq_gem_seqno = seqno;
+		trace_i915_gem_request_complete(dev, seqno);
+		DRM_WAKEUP(&dev_priv->irq_queue);
+		dev_priv->hangcheck_count = 0;
+		mod_timer(&dev_priv->hangcheck_timer, jiffies + DRM_I915_HANGCHECK_PERIOD);
+	}
 
-		/* check event from PCH */
-		if ((de_iir & DE_PCH_EVENT) &&
-			(pch_iir & SDE_HOTPLUG_MASK)) {
-			queue_work(dev_priv->wq, &dev_priv->hotplug_work);
-		}
+	if (de_iir & DE_GSE)
+		ironlake_opregion_gse_intr(dev);
 
-		de_iir = new_de_iir;
-		gt_iir = new_gt_iir;
-		pch_iir = new_pch_iir;
+	/* check event from PCH */
+	if ((de_iir & DE_PCH_EVENT) &&
+	    (pch_iir & SDE_HOTPLUG_MASK)) {
+		queue_work(dev_priv->wq, &dev_priv->hotplug_work);
 	}
 
+	/* should clear PCH hotplug event before clear CPU irq */
+	I915_WRITE(SDEIIR, pch_iir);
+	I915_WRITE(GTIIR, gt_iir);
+	I915_WRITE(DEIIR, de_iir);
+
+done:
 	I915_WRITE(DEIER, de_ier);
 	(void)I915_READ(DEIER);
 
-- 
1.6.3.3


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Open Source Technology Center, Intel ltd.

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