Re: [PATCH] PM / Domains: Replace -ENOSYS with -ENODEV

[Lukas Wunner <lukas@wunner.de>]

On Sat, Aug 06, 2016 at 12:17:58AM +0200, Rafael J. Wysocki wrote:
> On Fri, Aug 5, 2016 at 9:43 PM, Lukas Wunner <lukas@wunner.de> wrote:
> > On Fri, Aug 05, 2016 at 11:06:56AM -0600, Lina Iyer wrote:
> >> ENOSYS is for syscalls that are not supported. ENODEV is a better return
> >> value when the PM Domains are not available.
> >>
> >> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
> >
> > I have no opinion on this, but would like to point out that other parts
> > in the PM core use -ENOSYS as well (e.g. see drivers/base/power/core.c).

I meant drivers/base/power/runtime.c and include/linux/pm_runtime.h,
apologies.

> > For consistency, if pm_domain.h is changed, the rest should probably be
> > changed as well.
> 
> I agree here.  Changing one piece only is likely to result in confusion.
> 
> Also I'm not sure if ENODEV is a good replacement at all.  ENOTSUPP
> was suggested instead last time a similar patch was discussed.
> 
> > It should also be kept in mind that functions might
> > check the return code and react specifically to the currently used -ENOSYS.
> > (I've written code like that just yesterday, for the (unmerged) thunderbolt
> > runtime pm.)
> 
> But I wouldn't write code doing something like this.

Understood, I just removed it from my tree. :-)

Thanks,

Lukas