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

From: Guenter Roeck
Date: Fri Jan 27 2017 - 13:29:09 EST

On Fri, Jan 27, 2017 at 10:40:33PM +0800, Zhang Rui wrote:
> > >
> > > 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?

Let's go back to the basics.

Fact is that the thermal subsystem registers hwmon devices with 'name'
attributes which violate the documented hardware monitoring ABI.
I think we can consider this undisputed.

The rest is pretty much all opinion.

Is a change in a driver to stop violating a documented ABI an ABI change
or a bug fix ? In other words, does a driver violating a documented ABI
make that ABI violation part of the ABI ?

Quite interesting questions. My take is that it is a bug fix, others
apparently have the strong opinion that potential users of such an ABI
violation have priority, and that a violation of a documented ABI _does_
make this violation part of the ABI.

I'll leave it at that. I tried to make my position clear, but it appears
that I am quite alone in my opinion. With that, I'll leave it up to you to
decide how to proceed.