Re: [PATCH v1 0/6] Introduce power off call chain API

[Andy Shevchenko]

On Thu, Oct 07, 2021 at 11:52:46AM +0300, Dmitry Osipenko wrote:
> 07.10.2021 10:18, Andy Shevchenko пишет:
> > On Thu, Oct 7, 2021 at 9:05 AM Dmitry Osipenko <digetx@xxxxxxxxx> wrote:

...

> >> This
> >> is a somewhat simplified version which doesn't try to convert whole kernel
> >> to the new API at once, but solves immediate practical problem that we
> > 
> > problems
> > 
> >> have on Nexus 7 Android tablet where device needs to chain power off
> > 
> > tablets where the device
> 
> Thank you for the corrections, so far there is one problem and one tablet :)

Then use "the Nexus 7 Android tablet" :-)

> > Immediate question here is how do you see the plan of spreading this.
> > I.o.w. can you put an explanation that you have checked, let's say
> >> 80% current users, and they may be converted like [example
> > placeholder] without any special tricks?
> 
> The rough plan is:
> 
> 1. Add new API.
> 2. Convert drivers to the new API per subsystem.

I would suggest to show that you are actually into it by converting a couple of
the subsystems for the starter.

> 3. Expose do_kernel_restart().
> 4. Replace pm_power_off() with do_kernel_poweroff() per arch/, making
> power off similar to the restart that uses do_kernel_restart().
> 5. Remove do_kernel_restart() from kernel/reboot.c
> 
> Majority of pm_power_off() users shouldn't need the chaining and
> pm_power_off() doesn't conflict with the new API, so there is no need to
> rush the conversion.
> 
> The single-link chain users could be converted to the new API directly,
> this will remove some global variables. But at first should be better to
> gain more users who actually need the chained power off since they may
> have very specific requirements not covered by the current variant of
> the API and will be easier to evolve API with less users.

All above in one or another form should be in cover letter.

-- 
With Best Regards,
Andy Shevchenko