From: Bartosz Golaszewski <brgl@bgdev.pl>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Randy Dunlap <rdunlap@infradead.org>,
Linus Walleij <linus.walleij@linaro.org>,
Jonathan Corbet <corbet@lwn.net>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Kent Gibson <warthog618@gmail.com>,
linux-gpio <linux-gpio@vger.kernel.org>,
linux-doc <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Subject: Re: [PATCH 23/23] Documentation: gpio: add documentation for gpio-mockup
Date: Tue, 8 Sep 2020 19:03:30 +0200 [thread overview]
Message-ID: <CAMRc=MexhEbnxCN3aN57k4V-mO-vQL=+8z9QFEzOCPkmn16-XQ@mail.gmail.com> (raw)
In-Reply-To: <20200907122238.GA1849893@kroah.com>
On Mon, Sep 7, 2020 at 2:22 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Sep 07, 2020 at 02:06:15PM +0200, Bartosz Golaszewski wrote:
> > On Mon, Sep 7, 2020 at 1:53 PM Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> wrote:
> > >
> > > On Mon, Sep 07, 2020 at 12:26:34PM +0200, Bartosz Golaszewski wrote:
> > > > On Mon, Sep 7, 2020 at 11:59 AM Andy Shevchenko
> > > > <andriy.shevchenko@linux.intel.com> wrote:
> > > > >
> > > > > On Fri, Sep 04, 2020 at 08:15:59PM -0700, Randy Dunlap wrote:
> > > > > > On 9/4/20 8:45 AM, Bartosz Golaszewski wrote:
> > > > >
> > > > > ...
> > > > >
> > > > > > > +GPIO Testing Driver
> > > > > > > +===================
> > > > > > > +
> > > > > > > +The GPIO Testing Driver (gpio-mockup) provides a way to create simulated GPIO
> > > > > > > +chips for testing purposes. There are two ways of configuring the chips exposed
> > > > > > > +by the module. The lines can be accessed using the standard GPIO character
> > > > > > > +device interface as well as manipulated using the dedicated debugfs directory
> > > > > > > +structure.
> > > > > >
> > > > > > Could configfs be used for this instead of debugfs?
> > > > > > debugfs is ad hoc.
> > > > >
> > > > > Actually sounds like a good idea.
> > > > >
> > > >
> > > > Well, then we can go on and write an entirely new mockup driver
> > > > (ditching module params and dropping any backwards compatibility)
> > > > because we're already using debugfs for line values.
> > > >
> > > > How would we pass the device properties to configfs created GPIO chips
> > > > anyway? Devices seem to only be created using mkdir. Am I missing
> > > > something?
> > >
> > > Same way how USB composite works, no?
> > >
> >
> > OK, so create a new chip directory in configfs, configure it using
> > some defined configfs attributes and then finally instantiate it from
> > sysfs?
> >
> > Makes sense and is probably the right way to go. Now the question is:
> > is it fine to just entirely remove the previous gpio-mockup? Should we
> > keep some backwards compatibility? Should we introduce an entirely new
> > module and have a transition period before removing previous
> > gpio-mockup?
> >
> > Also: this is a testing module so to me debugfs is just fine. Is
> > configfs considered stable ABI like sysfs?
>
> Yes it is. Or at least until you fix all existing users so that if you
> do change it, no one notices it happening :)
>
Got it. One more question: the current debugfs interface we're using
in gpio-mockup exists to allow to read current values of GPIO lines in
output mode (check how the user drives dummy lines) and to set their
simulated pull-up/pull-down resistors (what values the user reads in
input mode).
This works like this: in /sys/kernel/debug/gpio-mockup every dummy
chip creates its own directory (e.g.
/sys/kernel/debug/gpio-mockup/gpiochip0) and inside this directory
there's an attribute per line named after the line's offset (e.g.
/sys/kernel/debug/gpio-mockup/gpiochip0/4). Writing 0 or 1 to this
attribute sets the pull resistor. Reading from it yields the current
value (0 or 1 as well).
This is pretty non-standard so I proposed to put it in debugfs. If we
were to use configfs - is this where something like this should go? Or
rather sysfs? Is it even suitable/acceptable for sysfs?
Thanks,
Bartosz
next prev parent reply other threads:[~2020-09-08 17:04 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 15:45 [PATCH 00/23] gpio: mockup: support dynamically created and removed chips Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 01/23] lib: cmdline: export next_arg() Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 02/23] lib: string_helpers: provide kfree_strarray() Bartosz Golaszewski
2020-09-04 16:33 ` Andy Shevchenko
2020-09-04 15:45 ` [PATCH 03/23] lib: uaccess: provide getline_from_user() Bartosz Golaszewski
2020-09-04 16:35 ` Andy Shevchenko
2020-09-07 10:02 ` Bartosz Golaszewski
2020-09-07 10:18 ` Andy Shevchenko
2020-09-07 10:28 ` Bartosz Golaszewski
2020-09-07 11:45 ` Andy Shevchenko
2020-09-07 11:57 ` Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 04/23] gpiolib: generalize devprop_gpiochip_set_names() for device properties Bartosz Golaszewski
2020-09-04 16:38 ` Andy Shevchenko
2020-09-07 10:56 ` Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 05/23] gpiolib: unexport devprop_gpiochip_set_names() Bartosz Golaszewski
2020-09-04 16:40 ` Andy Shevchenko
2020-09-07 10:53 ` Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 06/23] gpiolib: switch to simpler IDA interface Bartosz Golaszewski
2020-09-04 16:41 ` Andy Shevchenko
2020-09-07 10:50 ` Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 07/23] gpio: mockup: drop unneeded includes Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 08/23] gpio: mockup: use pr_fmt() Bartosz Golaszewski
2020-09-04 16:29 ` Andy Shevchenko
2020-09-04 15:45 ` [PATCH 09/23] gpio: mockup: use KBUILD_MODNAME Bartosz Golaszewski
2020-09-04 16:30 ` Andy Shevchenko
2020-09-04 15:45 ` [PATCH 10/23] gpio: mockup: fix resource leak in error path Bartosz Golaszewski
2020-09-04 17:00 ` Andy Shevchenko
2020-09-07 11:04 ` Bartosz Golaszewski
2020-09-07 11:47 ` Andy Shevchenko
2020-09-04 15:45 ` [PATCH 11/23] gpio: mockup: remove the limit on number of dummy chips Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 12/23] gpio: mockup: define a constant for chip label size Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 13/23] gpio: mockup: pass the chip label as device property Bartosz Golaszewski
2020-09-04 16:48 ` Andy Shevchenko
2020-09-07 11:01 ` Bartosz Golaszewski
2020-09-07 11:48 ` Andy Shevchenko
2020-09-04 15:45 ` [PATCH 14/23] gpio: mockup: use the generic 'gpio-line-names' property Bartosz Golaszewski
2020-09-04 16:46 ` Andy Shevchenko
2020-09-07 10:58 ` Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 15/23] gpio: mockup: use dynamic device IDs Bartosz Golaszewski
2020-09-04 16:49 ` Andy Shevchenko
2020-09-07 11:04 ` Bartosz Golaszewski
2020-09-07 11:50 ` Andy Shevchenko
2020-09-07 11:59 ` Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 16/23] gpio: mockup: refactor the module init function Bartosz Golaszewski
2020-09-04 16:50 ` Andy Shevchenko
2020-09-07 11:05 ` Bartosz Golaszewski
2020-09-07 11:51 ` Andy Shevchenko
2020-09-04 15:45 ` [PATCH 17/23] gpio: mockup: rename and move around debugfs callbacks Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 18/23] gpio: mockup: require debugfs to build Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 19/23] gpio: mockup: add a symlink for the per-chip debugfs directory Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 20/23] gpio: mockup: add a lock for dummy device list Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 21/23] gpio: mockup: provide a way to delete dummy chips Bartosz Golaszewski
2020-09-04 16:56 ` Andy Shevchenko
2020-09-04 15:45 ` [PATCH 22/23] gpio: mockup: provide a way to create new " Bartosz Golaszewski
2020-09-04 15:45 ` [PATCH 23/23] Documentation: gpio: add documentation for gpio-mockup Bartosz Golaszewski
2020-09-04 16:58 ` Andy Shevchenko
2020-09-05 3:15 ` Randy Dunlap
2020-09-07 9:59 ` Andy Shevchenko
2020-09-07 10:26 ` Bartosz Golaszewski
2020-09-07 11:53 ` Andy Shevchenko
2020-09-07 12:06 ` Bartosz Golaszewski
2020-09-07 12:22 ` Greg Kroah-Hartman
2020-09-07 13:49 ` Bartosz Golaszewski
2020-09-07 14:08 ` Andy Shevchenko
2020-09-07 15:14 ` Bartosz Golaszewski
2020-09-07 15:23 ` Geert Uytterhoeven
2020-09-07 16:08 ` Bartosz Golaszewski
2020-09-08 17:03 ` Bartosz Golaszewski [this message]
2020-09-11 12:56 ` Greg Kroah-Hartman
2020-09-11 13:07 ` Bartosz Golaszewski
2020-09-07 12:38 ` Andy Shevchenko
2020-09-07 12:57 ` Bartosz Golaszewski
2020-09-07 13:52 ` Andy Shevchenko
2020-09-07 10:45 ` Bartosz Golaszewski
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