From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
To: Kent Gibson <warthog618@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH v2 05/18] gpiolib: cdev: support GPIO_GET_LINE_IOCTL and GPIOLINE_GET_VALUES_IOCTL
Date: Mon, 3 Aug 2020 22:02:50 +0200 [thread overview]
Message-ID: <CAMpxmJWZpMFbrMBkLiR9q7chdamVnjw0geDf-pgKrz=AWD8mNg@mail.gmail.com> (raw)
In-Reply-To: <20200802033158.GA13174@sol>
On Sun, Aug 2, 2020 at 5:32 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> On Fri, Jul 31, 2020 at 06:05:10PM +0200, Bartosz Golaszewski wrote:
> > On Sun, Jul 26, 2020 at 3:12 AM Kent Gibson <warthog618@gmail.com> wrote:
[snip!]
> > > >
> > > > > +static u64 gpioline_config_flags(struct gpioline_config *lc, int line_idx)
> > > > > +{
> > > > > + int i;
> > > > > +
> > > > > + for (i = lc->num_attrs - 1; i >= 0; i--) {
> > > >
> > > > Much better to read is
> > > >
> > > > unsigned int i = lc->num_attrs;
> > > >
> > > > while (i--) {
> > > > ...
> > > > }
> > > >
> > >
> > > Really? I find that the post-decrement in the while makes determining the
> > > bounds of the loop more confusing.
> > >
> >
> > Agreed, Andy: this is too much nit-picking. :)
> >
>
> I was actually hoping for some feedback on the direction of that loop,
> as it relates to the handling of multiple instances of the same
> attribute associated with a given line.
>
> The reverse loop here implements a last in wins policy, but I'm now
> thinking the kernel should be encouraging userspace to only associate a
> given attribute with a line once, and that a first in wins would help do
> that - as additional associations would be ignored.
>
> Alternatively, the kernel should enforce that an attribute can only be
> associated once, but that would require adding more request validation.
>
I guess this would result in a lot of churn to do validation which is
largely unnecessary? To me the first in wins sounds more consistent.
Also: I just started going through the patches - nice idea with the
GPIO attributes, I really like it. Although I need to give it a longer
thought tomorrow - I'm wondering if we can maybe unify them and the
flags.
[snip]
Bartosz
next prev parent reply other threads:[~2020-08-03 20:03 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-25 4:19 [PATCH v2 00/18] gpio: cdev: add uAPI V2 Kent Gibson
2020-07-25 4:19 ` [PATCH v2 01/18] gpio: uapi: define GPIO_MAX_NAME_SIZE for array sizes Kent Gibson
2020-07-25 4:19 ` [PATCH v2 02/18] gpio: uapi: define uAPI v2 Kent Gibson
2020-08-04 17:42 ` Bartosz Golaszewski
2020-08-05 5:18 ` Kent Gibson
2020-08-05 17:47 ` Bartosz Golaszewski
2020-08-06 1:03 ` Kent Gibson
2020-08-06 1:15 ` Kent Gibson
2020-08-06 15:53 ` Bartosz Golaszewski
2020-07-25 4:19 ` [PATCH v2 03/18] gpiolib: make cdev a build option Kent Gibson
2020-07-25 20:29 ` Andy Shevchenko
2020-07-26 22:25 ` Linus Walleij
2020-07-27 1:46 ` Kent Gibson
2020-07-27 5:57 ` Kent Gibson
2020-07-27 8:15 ` Linus Walleij
2020-07-25 4:19 ` [PATCH v2 04/18] gpiolib: add build option for CDEV v1 ABI Kent Gibson
2020-07-25 4:19 ` [PATCH v2 05/18] gpiolib: cdev: support GPIO_GET_LINE_IOCTL and GPIOLINE_GET_VALUES_IOCTL Kent Gibson
2020-07-25 20:51 ` Andy Shevchenko
2020-07-26 1:12 ` Kent Gibson
2020-07-26 3:24 ` Kent Gibson
2020-07-29 2:28 ` Kent Gibson
2020-07-29 8:05 ` Andy Shevchenko
2020-07-29 10:01 ` Kent Gibson
2020-07-31 16:05 ` Bartosz Golaszewski
2020-08-02 3:31 ` Kent Gibson
2020-08-02 9:32 ` Kent Gibson
2020-08-03 19:59 ` Bartosz Golaszewski
2020-08-03 20:02 ` Bartosz Golaszewski [this message]
2020-08-03 23:01 ` Kent Gibson
2020-08-04 17:47 ` Bartosz Golaszewski
2020-08-05 3:06 ` Kent Gibson
2020-07-25 4:19 ` [PATCH v2 06/18] gpiolib: cdev: support GPIO_GET_LINEINFO_V2_IOCTL and GPIO_GET_LINEINFO_WATCH_V2_IOCTL Kent Gibson
2020-07-25 4:19 ` [PATCH v2 07/18] gpiolib: cdev: support edge detection for uAPI v2 Kent Gibson
2020-08-04 19:28 ` Bartosz Golaszewski
2020-07-25 4:19 ` [PATCH v2 08/18] gpiolib: cdev: support GPIOLINE_SET_CONFIG_IOCTL Kent Gibson
2020-07-25 4:19 ` [PATCH v2 09/18] gpiolib: cdev: support GPIOLINE_SET_VALUES_IOCTL Kent Gibson
2020-07-25 4:19 ` [PATCH v2 10/18] gpiolib: cdev: support setting debounce Kent Gibson
2020-07-25 4:19 ` [PATCH v2 11/18] gpio: uapi: document uAPI v1 as deprecated Kent Gibson
2020-08-04 19:43 ` Bartosz Golaszewski
2020-07-25 4:19 ` [PATCH v2 12/18] tools: gpio: port lsgpio to v2 uAPI Kent Gibson
2020-07-25 4:19 ` [PATCH v2 13/18] tools: gpio: port gpio-watch " Kent Gibson
2020-07-25 4:19 ` [PATCH v2 14/18] tools: gpio: rename nlines to num_lines Kent Gibson
2020-07-25 4:19 ` [PATCH v2 15/18] tools: gpio: port gpio-hammer to v2 uAPI Kent Gibson
2020-07-25 4:19 ` [PATCH v2 16/18] tools: gpio: port gpio-event-mon " Kent Gibson
2020-07-25 4:19 ` [PATCH v2 17/18] tools: gpio: add debounce support to gpio-event-mon Kent Gibson
2020-07-25 4:19 ` [PATCH v2 18/18] tools: gpio: add multi-line monitoring " Kent Gibson
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