Re: [PATCH/RFC 1/2] PM / wakeup: Add callback for wake-up change notification

[Rafael J. Wysocki]

First, sorry for the huge delay.

On Wednesday, March 14, 2018 12:26:24 PM CEST Geert Uytterhoeven wrote:
> Add a callback to inform a device that his wake-up setting has been
> changed.  This allows a device to synchronize device configuration with
> an external user action.
> 
> E.g. on systems using a Rohm BD9571MWV PMIC and a toggle accessory power
> switch, the system suspend procedure is:
>   1. Configure PMIC for DDR backup mode, which changes the role of the
>      accessory power switch from a power to a wake-up switch,
>   2. Switch accessory power switch off, to prepare for system suspend,
>   3. Suspend system.
> 
> Hence step 1 cannot be done in the PMIC's suspend callback,

I don't quite understand this, so can you please explain?

What can't it be done from ->prepare() or even from a suspend notifier?

> but it can be done in the new callback, in response to the user writing "enabled"
> to the PMIC's wakeup virtual file in sysfs.