cpuidle acpi driver: fix oops on AC<->DC

cpuidle and acpi driver interaction bug with the way cpuidle_register_driver()
is called. Due to this bug, there will be oops on
AC<->DC on some systems, where they support C-states in one DC and not in AC.

The current code does
ON BOOT:
	Look at CST and other C-state info to see whether more than C1 is
	supported. If it is, then acpi processor_idle does a
	cpuidle_register_driver() call, which internally enables the device.

ON CST change notification (AC<->DC) and on suspend-resume:
	acpi driver temporarily disables device, updates the device with
	any new C-states, and reenables the device.

The problem is is on boot, there are no C2, C3 states supported and we skip
the register. Later on AC<->DC, we may get a CST notification and we try
to reevaluate CST and enabled the device, without actually registering it.
This causes breakage as we try to create /sys fs sub directory, without the
parent directory which is created at register time.

Thanks to Sanjeev for reporting the problem here.
http://bugzilla.kernel.org/show_bug.cgi?id=10394

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 51e6b1e520e..dcf77fa826b 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -82,6 +82,7 @@ struct cpuidle_state_kobj {
 };
 
 struct cpuidle_device {
+	unsigned int		registered:1;
 	unsigned int		enabled:1;
 	unsigned int		cpu;