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    SubjectRe: [PATCH v5 00/20] gpio: cdev: add uAPI v2
    On Tue, Sep 01, 2020 at 11:28:13AM +0200, Bartosz Golaszewski wrote:
    > On Sat, Aug 29, 2020 at 3:35 AM Kent Gibson <warthog618@gmail.com> wrote:
    > >
    > > On Fri, Aug 28, 2020 at 04:37:19PM +0200, Linus Walleij wrote:
    > > > On Fri, Aug 28, 2020 at 12:47 AM Kent Gibson <warthog618@gmail.com> wrote:
    > > >
    > > > > The particular use case I am considering is one I had been asked about -
    > > > > changing a requested line from input with edge detection to output, and
    > > > > vice versa. Losing interrupts isn't really an issue for this use case -
    > > > > it is expected. Yet the current implementation requires a re-request.
    > > >
    > > > This is possible to do for in-kernel users, but I don't know if that makes
    > > > sense for userspace. It is for one-offs and prototyping after all, there
    > > > is no need (IMO) to make it overly convenient for users to implement
    > > > all kind of weirdness in userspace unless there is a very real use case.
    > > >
    > >
    > > Fair point - in fact it is the same one that made me reconsider why I
    > > was so concerned about potentially losing an edge event in a few rare
    > > corner cases.
    > >
    > > Another point for this change are that it actually simplifies the kernel
    > > code, as it takes as much code to detect and filter these cases as it
    > > does to include them in the normal flow.
    > >
    > > I had a play with it yesterday and the change removes two whole
    > > functions, gpio_v2_line_config_change_validate() and
    > > gpio_v2_line_config_has_edge_detection() at the expense of making
    > > debounce_update() a little more complicated. I'm happy to put together a
    > > v6 that incorporates those changes if there aren't any strenuous
    > > objections - we can always revert to v5. Or I could mail the couple of
    > > patches I've made and if they seem reasonable then I could merge them
    > > into this set?
    > >
    > > Cheers,
    > > Kent.
    >
    > I personally like v6 more. The code is more elegant and we've also
    > tried limiting GPIO chardev features before and now we're doing v2 so
    > let's not make the same mistake twice. :)
    >
    > I'll try to review v6 in detail later today.

    Let me briefly review to this. Can you remind which patch has a top level
    description of what features are provided in comparison to uAPI v1?
    (Btw, do we have some kind of comparison table?)


    --
    With Best Regards,
    Andy Shevchenko


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