[ 3.5.y.z extended stable ] Patch "rapidio/tsi721: fix bug in MSI interrupt handling" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    rapidio/tsi721: fix bug in MSI interrupt handling

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 15cd6017ec39826eb5e0ad319b3a111233cd9f18 Mon Sep 17 00:00:00 2001
From: Alexandre Bounine <alexandre.bounine at idt.com>
Date: Fri, 24 May 2013 15:55:17 -0700
Subject: [PATCH] rapidio/tsi721: fix bug in MSI interrupt handling

commit 1ccc819da6fda9bee10ab8b72e9adbb5ad3e4959 upstream.

Fix bug in MSI interrupt handling which causes loss of event
notifications.

Typical indication of lost MSI interrupts are stalled message and
doorbell transfers between RapidIO endpoints.  To avoid loss of MSI
interrupts all interrupts from the device must be disabled on entering
the interrupt handler routine and re-enabled when exiting it.
Re-enabling device interrupts will trigger new MSI message(s) if Tsi721
registered new events since entering interrupt handler routine.

This patch is applicable to kernel versions starting from v3.2.

Signed-off-by: Alexandre Bounine <alexandre.bounine at idt.com>
Cc: Matt Porter <mporter at kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/rapidio/devices/tsi721.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/rapidio/devices/tsi721.c b/drivers/rapidio/devices/tsi721.c
index 5d44252..7fca1da 100644
--- a/drivers/rapidio/devices/tsi721.c
+++ b/drivers/rapidio/devices/tsi721.c
@@ -471,6 +471,10 @@ static irqreturn_t tsi721_irqhandler(int irq, void *ptr)
 	u32 intval;
 	u32 ch_inte;

+	/* For MSI mode disable all device-level interrupts */
+	if (priv->flags & TSI721_USING_MSI)
+		iowrite32(0, priv->regs + TSI721_DEV_INTE);
+
 	dev_int = ioread32(priv->regs + TSI721_DEV_INT);
 	if (!dev_int)
 		return IRQ_NONE;
@@ -560,6 +564,14 @@ static irqreturn_t tsi721_irqhandler(int irq, void *ptr)
 		}
 	}
 #endif
+
+	/* For MSI mode re-enable device-level interrupts */
+	if (priv->flags & TSI721_USING_MSI) {
+		dev_int = TSI721_DEV_INT_SR2PC_CH | TSI721_DEV_INT_SRIO |
+			TSI721_DEV_INT_SMSG_CH | TSI721_DEV_INT_BDMA_CH;
+		iowrite32(dev_int, priv->regs + TSI721_DEV_INTE);
+	}
+
 	return IRQ_HANDLED;
 }

--
1.8.1.2