Re: v4.10-rc4 to v4.10-rc5: battery regression on Nokia N900

From: Pavel Machek
Date: Fri Jan 27 2017 - 14:31:44 EST


> > > > That sounds like fun. Changing bq27200-0 to bq27200_0 is
> > > > Forbidden by
> > > > the ABI Police, but taking the entire device away is ok.
> > > >
> > > No. IMO, it depends on if the interface is used or not.
> > > If hwmon I/F is used, we can not take it away, nor change its name.
> > Even if the use doesn't depend on that name ?
> >
> when I said "the interface is used", I mean the name string is used.
> > >
> > > If thermal zone I/F is used, we can not change it's 'type' name to
> > > be
> > > compatible with new hwmon API.
> > >
> > You mean you can not fix the name to be compatible with libsensors.
> >
> We can try to convert it to a libsensor-compatible string, either for
> hwmon only, or for both thermal and hwmon. But this is an ABI change,
> right?
> And my understanding about the ABI change is that, if no one cares
> about it, we're okay, or else, this is a regression, and we need to
> fall back to the previous ABI immediately. In order to change it in a
> long run, we need to make a note in Documentation/ABI/, and change it
> sometime in the future (a couple of release cycles or even more).

If no one cares, you can get away with the change. So I guess that's
what we should try. In -rc1. We should _not_ do "this changes in 2
years" dance, as that would increase chance for someone to use the old

So I guess changing to libsensor-compatible name in v4.11-rc0 (maybe
with note in the ABI documenation) is the best plan. If someone
complains, we'll have to revert and think about something else.

(cesky, pictures)

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