[PATCH v2] leds: fix hibernation on arm when gpio-led used with CPU led trigger

[grygorii.strashko at linaro.org]

From: Grygorii Strashko <Grygorii.Strashko at linaro.org>

Setting a dev_pm_ops suspend/resume pair of callbacks but not a set of
hibernation callbacks means those pm functions will not be
called upon hibernation - that leads to system crash on ARM during
freezing if gpio-led is used in combination with CPU led trigger.
It may happen after freeze_noirq stage (GPIO is suspended)
and before syscore_suspend stage (CPU led trigger is suspended)
- usually when disable_nonboot_cpus() is called.

Log:
  PM: noirq freeze of devices complete after 1.425 msecs
  Disabling non-boot CPUs ...
    ^ system may crash or stuck here with message (TI AM572x)

  WARNING: CPU: 0 PID: 3100 at drivers/bus/omap_l3_noc.c:148 l3_interrupt_handler+0x22c/0x370()
  44000000.ocp:L3 Custom Error: MASTER MPU TARGET L4_PER1_P3 (Idle): Data Access in Supervisor mode during Functional access

  CPU1: shutdown
    ^ or here

Fix this by using SIMPLE_DEV_PM_OPS, which appropriately
assigns the suspend and hibernation callbacks and move
led_suspend/led_resume under CONFIG_PM_SLEEP to avoid
build warnings.

Signed-off-by: Grygorii Strashko <Grygorii.Strashko at linaro.org>
---
This patch actually fixes commit:
 73e1ab4 "leds: Convert led class driver from legacy pm ops to dev_pm_ops"

Changes in v2:
- fixed compile time warnings when !CONFIG_PM_SLEEP
- updated commit message

v1:
- https://lkml.org/lkml/2015/2/2/476

 drivers/leds/led-class.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index dbeebac..5033e0d 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -183,6 +183,7 @@ void led_classdev_resume(struct led_classdev *led_cdev)
 }
 EXPORT_SYMBOL_GPL(led_classdev_resume);
 
+#ifdef CONFIG_PM_SLEEP
 static int led_suspend(struct device *dev)
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
@@ -202,11 +203,9 @@ static int led_resume(struct device *dev)
 
 	return 0;
 }
+#endif
 
-static const struct dev_pm_ops leds_class_dev_pm_ops = {
-	.suspend        = led_suspend,
-	.resume         = led_resume,
-};
+static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
 
 /**
  * led_classdev_register - register a new object of led_classdev class.
-- 
1.9.1