[kernel/f16] Fix crash when setting brightness via Fn keys on ideapads (rhbz 748210)

[Josh Boyer]

commit 3be61a8c6020efec748f59e1b0e30ea0f1387025
Author: Josh Boyer <jwboyer at redhat.com>
Date:   Thu Nov 3 09:49:33 2011 -0400

    Fix crash when setting brightness via Fn keys on ideapads (rhbz 748210)

 ...ad-Check-if-acpi-already-handle-backlight.patch |   31 ++++++++++++++++++++
 kernel.spec                                        |    7 ++++
 2 files changed, 38 insertions(+), 0 deletions(-)
---
diff --git a/ideapad-Check-if-acpi-already-handle-backlight.patch b/ideapad-Check-if-acpi-already-handle-backlight.patch
new file mode 100644
index 0000000..713e005
--- /dev/null
+++ b/ideapad-Check-if-acpi-already-handle-backlight.patch
@@ -0,0 +1,31 @@
+From d4afc7754a60b885b63ef23fd194984e2d53a4e6 Mon Sep 17 00:00:00 2001
+From: Rene Bollford <xsecute at googlemail.com>
+Date: Sun, 23 Oct 2011 09:56:42 +0200
+Subject: [PATCH] [PATCH] ideapad: Check if acpi already handle backlight
+ power to avoid a page fault
+
+This patch avoid a page fault in the ideapad-laptop extras when
+turning the backlight power on or off.
+
+Signed-off-by: Rene Bolldorf <xsecute at googlemail.com>
+Signed-off-by: Matthew Garrett <mjg at redhat.com>
+---
+ drivers/platform/x86/ideapad-laptop.c |    2 ++
+ 1 files changed, 2 insertions(+), 0 deletions(-)
+
+diff --git a/drivers/platform/x86/ideapad-laptop.c b/drivers/platform/x86/ideapad-laptop.c
+index 0c59541..0d94eec 100644
+--- a/drivers/platform/x86/ideapad-laptop.c
++++ b/drivers/platform/x86/ideapad-laptop.c
+@@ -493,6 +493,8 @@ static void ideapad_backlight_notify_power(struct ideapad_private *priv)
+ 	unsigned long power;
+ 	struct backlight_device *blightdev = priv->blightdev;
+ 
++	if (!blightdev)
++		return;
+ 	if (read_ec_data(ideapad_handle, 0x18, &power))
+ 		return;
+ 	blightdev->props.power = power ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
+-- 
+1.7.6.4
+
diff --git a/kernel.spec b/kernel.spec
index e8e2ca5..42279c0 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -771,6 +771,9 @@ Patch21071: WMI-properly-cleanup-devices-to-avoid-crashes.patch
 #rhbz 728607
 Patch21060: elantech.patch
 
+#rhbz 748210
+Patch21061: ideapad-Check-if-acpi-already-handle-backlight.patch
+
 %endif
 
 BuildRoot: %{_tmppath}/kernel-%{KVERREL}-root
@@ -1422,6 +1425,9 @@ ApplyPatch WMI-properly-cleanup-devices-to-avoid-crashes.patch
 #rhbz 728607
 ApplyPatch elantech.patch
 
+#rhbz 748210
+ApplyPatch ideapad-Check-if-acpi-already-handle-backlight.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2125,6 +2131,7 @@ fi
 %changelog
 * Thu Nov 03 2011 Josh Boyer <jwboyer at redhat.com>
 - Add commits queued for 3.2 for elantech driver (rhbz 728607)
+- Fix crash when setting brightness via Fn keys on ideapads (rhbz 748210)
 
 * Wed Nov 02 2011 Josh Boyer <jwboyer at redhat.com>
 - Add patch to fix oops when removing wmi module (rhbz 706574)