From: Linus Walleij <linus.walleij@linaro.org>
To: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Kent Gibson <warthog618@gmail.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: Re: [RESEND PATCH v6 6/7] gpiolib: add new ioctl() for monitoring changes in line info
Date: Wed, 12 Feb 2020 11:47:31 +0100 [thread overview]
Message-ID: <CACRpkdZNyCBxQF_pVPGENob5EKZfYjuaNq5bLNA42XjraXzNZg@mail.gmail.com> (raw)
In-Reply-To: <20200211091937.29558-7-brgl@bgdev.pl>
On Tue, Feb 11, 2020 at 10:19 AM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Currently there is no way for user-space to be informed about changes
> in status of GPIO lines e.g. when someone else requests the line or its
> config changes. We can only periodically re-read the line-info. This
> is fine for simple one-off user-space tools, but any daemon that provides
> a centralized access to GPIO chips would benefit hugely from an event
> driven line info synchronization.
>
> This patch adds a new ioctl() that allows user-space processes to reuse
> the file descriptor associated with the character device for watching
> any changes in line properties. Every such event contains the updated
> line information.
>
> Currently the events are generated on three types of status changes: when
> a line is requested, when it's released and when its config is changed.
> The first two are self-explanatory. For the third one: this will only
> happen when another user-space process calls the new SET_CONFIG ioctl()
> as any changes that can happen from within the kernel (i.e.
> set_transitory() or set_debounce()) are of no interest to user-space.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Looks good to me. This got really slim and clean after
the reviews, and I am of course also impressed by the kfifo
improvement this brings.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
A question:
Bartosz, since you know about possible impacts on userspace,
since this code use the preferred ktime_get_ns() rather than
ktime_get_ns_real(), what happens if we just patch the other
event timestamp to use ktime_get_ns() instead, so we use the
same everywhere?
If it's fine I'd like to just toss in a patch for that as well.
Yours,
Linus Walleij
next prev parent reply other threads:[~2020-02-12 10:47 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 9:19 [RESEND PATCH v6 0/7] gpiolib: add an ioctl() for monitoring line status changes Bartosz Golaszewski
2020-02-11 9:19 ` [RESEND PATCH v6 1/7] kfifo: provide noirqsave variants of spinlocked in and out helpers Bartosz Golaszewski
2020-02-11 9:19 ` [RESEND PATCH v6 2/7] kfifo: provide kfifo_is_empty_spinlocked() Bartosz Golaszewski
2020-02-11 9:19 ` [RESEND PATCH v6 3/7] gpiolib: rework the locking mechanism for lineevent kfifo Bartosz Golaszewski
2020-02-11 9:19 ` [RESEND PATCH v6 4/7] gpiolib: emit a debug message when adding events to a full kfifo Bartosz Golaszewski
2020-02-11 9:19 ` [RESEND PATCH v6 5/7] gpiolib: provide a dedicated function for setting lineinfo Bartosz Golaszewski
2020-03-16 16:20 ` Geert Uytterhoeven
2020-03-17 13:40 ` Bartosz Golaszewski
2020-02-11 9:19 ` [RESEND PATCH v6 6/7] gpiolib: add new ioctl() for monitoring changes in line info Bartosz Golaszewski
2020-02-12 10:47 ` Linus Walleij [this message]
2020-02-12 11:00 ` Bartosz Golaszewski
2020-02-20 15:03 ` Linus Walleij
2020-02-20 15:06 ` Bartosz Golaszewski
2020-02-11 9:19 ` [RESEND PATCH v6 7/7] tools: gpio: implement gpio-watch Bartosz Golaszewski
2020-02-12 10:49 ` [RESEND PATCH v6 0/7] gpiolib: add an ioctl() for monitoring line status changes Linus Walleij
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CACRpkdZNyCBxQF_pVPGENob5EKZfYjuaNq5bLNA42XjraXzNZg@mail.gmail.com \
--to=linus.walleij@linaro.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=bgolaszewski@baylibre.com \
--cc=brgl@bgdev.pl \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=warthog618@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).