[lkml]   [2017]   [Jan]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] power: reset: Add MAX77620 support
Hi Thierry,

> > > [...]
> >
> > Please use register_restart_handler() instead. It has support for
> > priorities, is not arm specific and properly supports unregistering
> > (some handler with lower priority will take over). You can check
> > gpio-restart as an example for the API.
> >
> > If you have some other arm_pm_restart handler (those are tried first)
> > I suggest to convert that to the restart handler framework. Actually
> > it may be a good idea to convert all of them and drop arm_pm_restart,
> > since there are only 4 left:
> >
> > $ git grep "arm_pm_restart ="
> > drivers/firmware/psci.c: arm_pm_restart = psci_sys_reset;
> > arch/arm/mach-prima2/rstc.c: arm_pm_restart = sirfsoc_restart;
> > arch/arm/xen/enlighten.c: arm_pm_restart = xen_restart;
> > arch/arm/kernel/setup.c: arm_pm_restart = mdesc->restart;
> >
> > The first 3 should be easy to update and the last one could
> > be solved by registering a wrapper function as restart handler,
> > which calls mdesc->restart().
> I remember this not being the first time that this confuses me. And from
> looking around a little it seems like I'm not the only one.
> Do you know if there's ever been any attempts to formalize all of this
> by adding some sort of framework for this? That way some of the
> confusion may be removed and architecture-specific bits could be
> eliminated more easily.

We have a framework for restart handlers, which has been written
by Guenter Roeck [0] in 2014. You just have to call register_restart_handler()
during probe and unregister_restart_handler() during removal of
your reboot driver. All reboot drivers in drivers/power/reset use
that framework.

The restart handlers are invoked by calling do_kernel_restart()
based on their configured priority. That function is called by
the architecture's machine_restart() function. It's currently
used by mips, ppc, arm & arm64 as far as I can see. ARM's
implementation looks like this:

if (arm_pm_restart)
do_kernel_restart() /* reboot handler framework */

No such thing exists for poweroff. Guenter also wrote something for
that [1], but Linus intervened [2]. Anyways, pm_power_off is at
least architecture independent.


-- Sebastian
[unhandled content-type:application/pgp-signature]
 \ /
  Last update: 2017-01-20 00:10    [W:0.079 / U:17.252 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site