[PATCH] forcedeth: msi interrupts

[Ayaz Abdulla <aabdulla@nvidia.com>]

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This patch adds a workaround for lost MSI interrupts. There is a race
condition in the HW in which future interrupts could be missed. The
workaround is to toggle the MSI irq mask.

Added cleanup based on comments from Andrew Morton.

Signed-off-by: Ayaz Abdulla <aabdulla@nvidia.com>


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--- old/drivers/net/forcedeth.c	2008-06-03 16:16:26.000000000 -0400
+++ new/drivers/net/forcedeth.c	2008-06-06 13:19:50.000000000 -0400
@@ -3277,6 +3277,20 @@
 	dprintk(KERN_DEBUG "%s: link change notification done.\n", dev->name);
 }
 
+static void nv_msi_workaround(struct fe_priv *np)
+{
+
+	/* Need to toggle the msi irq mask within the ethernet device,
+	 * otherwise, future interrupts will not be detected.
+	 */
+	if (np->msi_flags & NV_MSI_ENABLED) {
+		u8 __iomem *base = np->base;
+
+		writel(0, base + NvRegMSIIrqMask);
+		writel(NVREG_MSI_VECTOR_0_ENABLED, base + NvRegMSIIrqMask);
+	}
+}
+
 static irqreturn_t nv_nic_irq(int foo, void *data)
 {
 	struct net_device *dev = (struct net_device *) data;
@@ -3299,6 +3313,8 @@
 		if (!(events & np->irqmask))
 			break;
 
+		nv_msi_workaround(np);
+
 		spin_lock(&np->lock);
 		nv_tx_done(dev);
 		spin_unlock(&np->lock);
@@ -3414,6 +3430,8 @@
 		if (!(events & np->irqmask))
 			break;
 
+		nv_msi_workaround(np);
+
 		spin_lock(&np->lock);
 		nv_tx_done_optimized(dev, TX_WORK_PER_LOOP);
 		spin_unlock(&np->lock);
@@ -3754,6 +3772,8 @@
 	if (!(events & NVREG_IRQ_TIMER))
 		return IRQ_RETVAL(0);
 
+	nv_msi_workaround(np);
+
 	spin_lock(&np->lock);
 	np->intr_test = 1;
 	spin_unlock(&np->lock);