[3.11.y.z extended stable] Patch "drm/qxl: return IRQ_NONE if it was not our irq" has been added to staging queue

[Luis Henriques]

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

    drm/qxl: return IRQ_NONE if it was not our irq

to the linux-3.11.y-queue branch of the 3.11.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-3.11.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 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From f22c54134ae2c653e3b88387e335d11e04cfedca Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang at redhat.com>
Date: Mon, 12 May 2014 16:35:39 +0800
Subject: drm/qxl: return IRQ_NONE if it was not our irq

commit fbb60fe35ad579b511de8604b06a30b43846473b upstream.

Return IRQ_NONE if it was not our irq. This is necessary for the case
when qxl is sharing irq line with a device A in a crash kernel. If qxl
is initialized before A and A's irq was raised during this gap,
returning IRQ_HANDLED in this case will cause this irq to be raised
again after EOI since kernel think it was handled but in fact it was
not.

Cc: Gerd Hoffmann <kraxel at redhat.com>
Signed-off-by: Jason Wang <jasowang at redhat.com>
Signed-off-by: Dave Airlie <airlied at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpu/drm/qxl/qxl_irq.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/qxl/qxl_irq.c b/drivers/gpu/drm/qxl/qxl_irq.c
index 21393dc4700a..f4b6b89b98f3 100644
--- a/drivers/gpu/drm/qxl/qxl_irq.c
+++ b/drivers/gpu/drm/qxl/qxl_irq.c
@@ -33,6 +33,9 @@ irqreturn_t qxl_irq_handler(DRM_IRQ_ARGS)

 	pending = xchg(&qdev->ram_header->int_pending, 0);

+	if (!pending)
+		return IRQ_NONE;
+
 	atomic_inc(&qdev->irq_received);

 	if (pending & QXL_INTERRUPT_DISPLAY) {
--
1.9.1