Re: [PATCH 2/5] gpio: davinci: Use dev name for label and automatic base selection

[David Lechner]

On 09/10/2018 02:37 AM, Sekhar Nori wrote:
> On Monday 10 September 2018 12:55 PM, Linus Walleij wrote:
> > On Sat, Sep 8, 2018 at 9:41 PM Grygorii Strashko
> > <grygorii.strashko@xxxxxx> wrote:
> > > On 09/06/2018 09:16 AM, Keerthy wrote:
> >
> > > > Okay now its numbered differently:
> > > >
> > > > cat /sys/class/gpio/gpiochip340/ngpio
> > > > 144
> > > >
> > > > cat /sys/class/gpio/gpiochip272/ngpio
> > > > 68
> > (...)
> >
> > So:
> >
> > > > > Are there applications that rely on the sysfs ABI on DaVinci?
> > > > >
> > > > > In that case base needs to be prerseved.
> > >
> > > Not only base, but label also - /sys/class/gpio/gpiochip0/label, as this is
> > > the way to find proper GPIO chip in sysfs using legacy GPIO ABI.
> > >
> > > Linus, this platform is old and most of the users do not use new ABI (chardev),
> > > so we could try change this, but need to be prepared for regressions reports.
> >
> > So what I'm trying to ask you guys is if there are applications that you
> > are aware of that use the old ABI, and who will upgrade their
> > kernels and be upset.
> >
> > We must not break userspace, but as you know if a tree falls in the
> > forest and nobody is there to hear it, it doesn't make a sound.
> >
> > If you're not aware of any such applications I guess we should try
> > changing this.
>
> Personally I am not really aware of any application which relies on the
> ABI. I may have some scripts, but I can adjust them. I am also copying
> some frequent users of DaVinci in mainline for any comments from them.
>
> Thanks,
> Sekhar

It won't break anything that I am aware of.