Re: [RFC PATCH] gpio: uapi: v2 proposal

[Kent Gibson <warthog618@xxxxxxxxx>]

On Thu, Jun 04, 2020 at 02:06:31PM +0200, Bartosz Golaszewski wrote:
> śr., 27 maj 2020 o 07:58 Linus Walleij <linus.walleij@xxxxxxxxxx> napisał(a):
> >
> > On Mon, May 25, 2020 at 4:19 PM Kent Gibson <warthog618@xxxxxxxxx> wrote:
> >
> > > > > +struct gpioline_config {
> > > > > +       __u8 default_values[GPIOLINES_MAX];
> > > >
> > > > So 32 bytes
> > > >
> > >
> > > Actually that one is 64 bytes, which is the same as v1, i.e. GPIOLINES_MAX
> > > is the same as GPIOHANDLES_MAX - just renamed.
> > >
> > > On the subject of values, is there any reason to use a byte for each line
> > > rather value than a bit?
> >
> > Not really, other than making things simple for userspace.
> >
> 
> I'm in favor of using bits here. I think we can rely on libgpiod to
> make things simple for user-space, the kernel interface can be as
> brief as possible.
> 

OK, I'll take another look at it.  If changed to a bitmap it will have
to be sized as a multiple of 64bits to maintain alignment.  Other than
that it should be pretty straight forward.

Cheers,
Kent.