Re: [PATCH v4 01/15] ARM: export arm_pm_restart()

[Lubomir Rintel]

On Tue, 2019-01-08 at 23:31 +0000, Russell King - ARM Linux wrote:
> On Tue, Jan 08, 2019 at 06:58:04PM +0100, Lubomir Rintel wrote:
> > The OLPC XO 1.75 laptop is rebooted with a command to the Embedded
> > Controller. The EC driver should be a module, since most people don't need
> > it to be compiled in.
> 
> Why do you need this - is there a reason why you can't hook onto the
> restart_handler_list using register_restart_handler()?  The registered
> handlers are passed the command.

Actually, yes. The restart handlers are invoked in atomic context, but
the EC communication needs to block. (The 1.75 EC is actually a SPI
master: a command it initiated by poking a GPIO and waiting until EC
tells us it's ready to read a command.)

Sorry for not mentioning that earlier, I forgot that it is the case.

> I would rather this is not exported to modules, it is generally unsafe
> to hook stuff by directly poking function pointers from module code.

Lubo