Re: [PATCH] ALSA: ac97: Switch to dev_pm_ops

On 08/07/2015 12:55 AM, Dmitry Torokhov wrote:
[...]

quoted

 
-#ifdef CONFIG_PM
-static int wm97xx_suspend(struct device *dev, pm_message_t state)
+#ifdef CONFIG_PM_SLEEP
+static int wm97xx_suspend(struct device *dev)

While we are changing it please drop #ifdef CONFIG_PM_SLEEP and annotate
suspend and resume with __maybe_unused.

We know that it is used when CONFIG_PM_SLEEP is defined and we know that it
is unused CONFIG_PM_SLEEP is not defined. Marking the function as
__maybe_unused will cause the compiler to not generate a warning when the
function is really unused. Making this explicit works much better.

quoted

 {
 	struct wm97xx *wm = dev_get_drvdata(dev);
 	u16 reg;

@@ -799,9 +799,11 @@ static int wm97xx_resume(struct device *dev)
 	return 0;
 }
 
+static SIMPLE_DEV_PM_OPS(wm97xx_pm_ops, wm97xx_suspend, wm97xx_resume);

Pull this out of #ifdef block and kill entire #else/endif along with
WM97XX_PM_OPS define: SIMPLE_DEV_PM_OPS will result in an empty
structure if CONFIG_PM_SLEEP is not set.

It will create a struct dev_pm_ops full of NULLs. That's kind of
counterproductive to removing PM related data and functions from the kernel
if PM support is no enabled.

quoted

+#define WM97XX_PM_OPS (&wm97xx_pm_ops)
+
 #else
-#define wm97xx_suspend		NULL
-#define wm97xx_resume		NULL
+#define WM97XX_PM_OPS NULL
 #endif

[...]