From: Kent Gibson <warthog618@gmail.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "Linus Walleij" <linus.walleij@linaro.org>,
"Bartosz Golaszewski" <bartosz.golaszewski@linaro.org>,
"Yury Norov" <yury.norov@gmail.com>,
linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
"Shubhrajyoti Datta" <shubhrajyoti.datta@amd.com>,
"Srinivas Neeli" <srinivas.neeli@amd.com>,
"Michal Simek" <michal.simek@amd.com>,
"Bartosz Golaszewski" <brgl@bgdev.pl>,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
"Marek Behún" <kabel@kernel.org>
Subject: Re: [PATCH v1 5/5] gpiolib: cdev: Utilize more bitmap APIs
Date: Mon, 2 Oct 2023 17:25:05 +0800 [thread overview]
Message-ID: <ZRqMcSffA7V77mqW@sol> (raw)
In-Reply-To: <ZRqHx+Ihcxor2Jz4@smile.fi.intel.com>
On Mon, Oct 02, 2023 at 12:05:11PM +0300, Andy Shevchenko wrote:
> On Wed, Sep 27, 2023 at 10:23:12PM +0800, Kent Gibson wrote:
> > On Wed, Sep 27, 2023 at 04:59:34PM +0300, Andy Shevchenko wrote:
> > > On Wed, Sep 27, 2023 at 09:49:35PM +0800, Kent Gibson wrote:
> > > > On Wed, Sep 27, 2023 at 03:17:06PM +0300, Andy Shevchenko wrote:
> > > > > On Wed, Sep 27, 2023 at 09:32:11AM +0800, Kent Gibson wrote:
>
> ...
>
> > > > > Yet, it opens a way to scale this in case we might have v3 ABI that let's say
> > > > > allows to work with 512 GPIOs at a time. With your code it will be much harder
> > > > > to achieve and see what you wrote about maintenance (in that case).
> > > >
> > > > v3 ABI?? libgpiod v2 is barely out the door!
> > > > Do you have any cases where 64 lines per request is limiting?
> > >
> > > IIRC it was SO question where the OP asks exactly about breaking the 64 lines
> > > limitation in the current ABI.
> > >
> > > > If that sort of speculation isn't premature optimisation then I don't know
> > > > what is.
> > >
> > > No, based on the real question / discussion, just have no link at hand.
> > > But it's quite a niche, I can agree.
> >
> > Let me know if you find a ref to that discussion - I'm curious.
>
> Here it is (read comments as well):
> https://stackoverflow.com/questions/76307370/control-gpio-from-linux-userspace-with-linux-gpio-h
>
That question looks to me to be confusing how many GPIOs can be
requested per request (64) and in total (effectively unlimited) - thinking
they are the same.
That could be due to their desire to use the gpiod_chip_get_all_lines()
convenience function with a chip with more than 64 lines, rather than
because they have an actual need for the lines to be managed in a single
request.
So that doesn't look like a genuine use case to me - just a "what if I
want to do X" question. Certainly not something that would warrant a v3
ABI.
Cheers,
Kent.
WARNING: multiple messages have this Message-ID (diff)
From: Kent Gibson <warthog618@gmail.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "Linus Walleij" <linus.walleij@linaro.org>,
"Bartosz Golaszewski" <bartosz.golaszewski@linaro.org>,
"Yury Norov" <yury.norov@gmail.com>,
linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
"Shubhrajyoti Datta" <shubhrajyoti.datta@amd.com>,
"Srinivas Neeli" <srinivas.neeli@amd.com>,
"Michal Simek" <michal.simek@amd.com>,
"Bartosz Golaszewski" <brgl@bgdev.pl>,
"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
"Marek Behún" <kabel@kernel.org>
Subject: Re: [PATCH v1 5/5] gpiolib: cdev: Utilize more bitmap APIs
Date: Mon, 2 Oct 2023 17:25:05 +0800 [thread overview]
Message-ID: <ZRqMcSffA7V77mqW@sol> (raw)
In-Reply-To: <ZRqHx+Ihcxor2Jz4@smile.fi.intel.com>
On Mon, Oct 02, 2023 at 12:05:11PM +0300, Andy Shevchenko wrote:
> On Wed, Sep 27, 2023 at 10:23:12PM +0800, Kent Gibson wrote:
> > On Wed, Sep 27, 2023 at 04:59:34PM +0300, Andy Shevchenko wrote:
> > > On Wed, Sep 27, 2023 at 09:49:35PM +0800, Kent Gibson wrote:
> > > > On Wed, Sep 27, 2023 at 03:17:06PM +0300, Andy Shevchenko wrote:
> > > > > On Wed, Sep 27, 2023 at 09:32:11AM +0800, Kent Gibson wrote:
>
> ...
>
> > > > > Yet, it opens a way to scale this in case we might have v3 ABI that let's say
> > > > > allows to work with 512 GPIOs at a time. With your code it will be much harder
> > > > > to achieve and see what you wrote about maintenance (in that case).
> > > >
> > > > v3 ABI?? libgpiod v2 is barely out the door!
> > > > Do you have any cases where 64 lines per request is limiting?
> > >
> > > IIRC it was SO question where the OP asks exactly about breaking the 64 lines
> > > limitation in the current ABI.
> > >
> > > > If that sort of speculation isn't premature optimisation then I don't know
> > > > what is.
> > >
> > > No, based on the real question / discussion, just have no link at hand.
> > > But it's quite a niche, I can agree.
> >
> > Let me know if you find a ref to that discussion - I'm curious.
>
> Here it is (read comments as well):
> https://stackoverflow.com/questions/76307370/control-gpio-from-linux-userspace-with-linux-gpio-h
>
That question looks to me to be confusing how many GPIOs can be
requested per request (64) and in total (effectively unlimited) - thinking
they are the same.
That could be due to their desire to use the gpiod_chip_get_all_lines()
convenience function with a chip with more than 64 lines, rather than
because they have an actual need for the lines to be managed in a single
request.
So that doesn't look like a genuine use case to me - just a "what if I
want to do X" question. Certainly not something that would warrant a v3
ABI.
Cheers,
Kent.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-10-02 9:25 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-26 5:20 [PATCH v1 0/5] bitmap: get rid of bitmap_remap() and bitmap_biremap() uses Andy Shevchenko
2023-09-26 5:20 ` Andy Shevchenko
2023-09-26 5:20 ` [PATCH v1 1/5] lib/test_bitmap: Excape space symbols when printing input string Andy Shevchenko
2023-09-26 5:20 ` Andy Shevchenko
2023-09-26 10:35 ` Kent Gibson
2023-09-26 10:35 ` Kent Gibson
2023-09-26 10:39 ` Kent Gibson
2023-09-26 10:39 ` Kent Gibson
2023-09-26 5:20 ` [PATCH v1 2/5] lib/bitmap: Introduce bitmap_scatter() and bitmap_gather() helpers Andy Shevchenko
2023-09-26 5:20 ` Andy Shevchenko
2023-09-27 0:25 ` Yury Norov
2023-09-27 0:25 ` Yury Norov
2023-09-27 2:10 ` Yury Norov
2023-09-27 2:10 ` Yury Norov
2023-09-27 12:10 ` Andy Shevchenko
2023-09-27 12:10 ` Andy Shevchenko
2023-09-27 12:02 ` Andy Shevchenko
2023-09-27 12:02 ` Andy Shevchenko
2023-10-02 4:06 ` Yury Norov
2023-10-02 4:06 ` Yury Norov
2023-10-02 8:23 ` Andy Shevchenko
2023-10-02 8:23 ` Andy Shevchenko
2023-09-26 5:20 ` [PATCH v1 3/5] gpio: xilinx: Switch to use new bitmap_scatter() helper Andy Shevchenko
2023-09-26 5:20 ` Andy Shevchenko
2023-09-26 5:20 ` [PATCH v1 4/5] gpio: xilinx: Replace bitmap_bitremap() calls Andy Shevchenko
2023-09-26 5:20 ` Andy Shevchenko
2023-09-26 10:41 ` Kent Gibson
2023-09-26 10:41 ` Kent Gibson
2023-09-26 11:11 ` Andy Shevchenko
2023-09-26 11:11 ` Andy Shevchenko
2023-09-26 11:17 ` Kent Gibson
2023-09-26 11:17 ` Kent Gibson
2023-09-26 5:20 ` [PATCH v1 5/5] gpiolib: cdev: Utilize more bitmap APIs Andy Shevchenko
2023-09-26 5:20 ` Andy Shevchenko
2023-09-27 0:46 ` Yury Norov
2023-09-27 0:46 ` Yury Norov
2023-09-27 6:48 ` Kent Gibson
2023-09-27 6:48 ` Kent Gibson
2023-09-27 1:32 ` Kent Gibson
2023-09-27 1:32 ` Kent Gibson
2023-09-27 12:17 ` Andy Shevchenko
2023-09-27 12:17 ` Andy Shevchenko
2023-09-27 13:49 ` Kent Gibson
2023-09-27 13:49 ` Kent Gibson
2023-09-27 13:59 ` Andy Shevchenko
2023-09-27 13:59 ` Andy Shevchenko
2023-09-27 14:23 ` Kent Gibson
2023-09-27 14:23 ` Kent Gibson
2023-10-02 9:05 ` Andy Shevchenko
2023-10-02 9:05 ` Andy Shevchenko
2023-10-02 9:25 ` Kent Gibson [this message]
2023-10-02 9:25 ` Kent Gibson
2023-10-02 9:32 ` Andy Shevchenko
2023-10-02 9:32 ` Andy Shevchenko
2023-10-02 9:42 ` Kent Gibson
2023-10-02 9:42 ` Kent Gibson
2023-09-26 8:52 ` [PATCH v1 0/5] bitmap: get rid of bitmap_remap() and bitmap_biremap() uses Linus Walleij
2023-09-26 8:52 ` Linus Walleij
2023-09-26 11:16 ` Andy Shevchenko
2023-09-26 11:16 ` Andy Shevchenko
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