Re: [libgpiod] [PATCH 11/19] API: add support for SET_CONFIG

[Kent Gibson <warthog618@gmail.com>]

On Wed, Nov 20, 2019 at 12:00:45PM +0100, Bartosz Golaszewski wrote:
> wt., 19 lis 2019 o 16:53 Kent Gibson <warthog618@gmail.com> napisał(a):
> >
> > On Mon, Nov 18, 2019 at 10:48:25PM +0800, Kent Gibson wrote:
> > > On Mon, Nov 18, 2019 at 02:52:04PM +0100, Bartosz Golaszewski
> > > > > +
> > > > > +int gpiod_line_set_flags_bulk(struct gpiod_line_bulk *bulk, int flags)
> > > > > +{
> > > > > +       struct gpiod_line *line;
> > > > > +       int values[GPIOD_LINE_BULK_MAX_LINES];
> > > > > +       unsigned int i;
> > > > > +       int direction;
> > > > > +
> > > > > +       line = gpiod_line_bulk_get_line(bulk, 0);
> > > > > +       if (line->as_is) {
> > > >
> > > > Can you explain the purpose of this as_is field? I'm not sure this is
> > > > really needed.
> > > >
> > >
> > > It is there for gpiod_set_flags, which has to populate the direction
> > > flags in the SET_CONFIG ioctl. The existing line->direction is
> > > either input or output.  It is drawn from GPIOLINE_FLAG_IS_OUT, so
> > > as-is is gets mapped to input.
> > > I didn't want to change the existing line->direction, and adding the
> > > as-is seemed clearer than adding another flavour of direction that
> > > contained all three.
> > >
> >
> > Hmmm, I think I see what you were getting at - the line->direction is the
> > direction from the kernel, so it doesn't hurt to use that value to set the
> > corresponding request flags - even if the original request was as-is??
> >
> > If that is the case then the line->as_is can be dropped throughout.
> >
> > Kent.
> >
> 
> Yes, this is what I was thinking. Just need to make sure the value
> from the kernel is up-to-date.
> 

So fail if needs_update?

Kent.