From: Linus Walleij <linus.walleij@linaro.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Geert Uytterhoeven" <geert@linux-m68k.org>,
"Bjorn Andersson" <bjorn.andersson@linaro.org>,
"Bartosz Golaszewski" <bgolaszewski@baylibre.com>,
"Enrico Weigelt, metux IT consult" <info@metux.net>,
"Viresh Kumar" <vireshk@kernel.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Jason Wang" <jasowang@redhat.com>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Bill Mills" <bill.mills@linaro.org>,
"Alex Bennée" <alex.bennee@linaro.org>,
stratos-dev@op-lists.linaro.org,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Stefano Garzarella --cc virtualization @ lists .
linux-foundation . org" <sgarzare@redhat.com>,
virtualization@lists.linux-foundation.org,
"Alistair Strachan" <astrachan@google.com>,
"Wolfram Sang" <wsa+renesas@sang-engineering.com>
Subject: Re: [PATCH V3 1/3] gpio: Add virtio-gpio driver
Date: Tue, 15 Jun 2021 22:03:21 +0200 [thread overview]
Message-ID: <CACRpkdbyybnxP9p3Jh2TbJMhK+kfLyed-YyrZq9JbOqu1csmww@mail.gmail.com> (raw)
In-Reply-To: <20210615111551.7tcz7teqp4olhodf@vireshk-i7>
On Tue, Jun 15, 2021 at 1:15 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> I am now wondering how interrupts can be made to work here. Do you
> have anything in mind for that ?
The aggregator does not aggregate interrupts only lines for now.
> GPIO sysfs already supports interrupts, (...)
I hope that doesn't make you tempted to use sysfs to get interrupts,
those are awful, they use sysfs_notify_dirent() which means that
if two IRQs happen in fast succession you will miss one of them
and think it was only one.
The GPIO character device supports low latency events forwarding
interrupts to userspace including QEMU & similar, timestamps the
events as close in time as possible to when they actually happen
(which is necessary for any kind of industrial control) and will never
miss an event if the hardware can register it. See:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/gpio/gpio-event-mon.c
Yours,
Linus Walleij
WARNING: multiple messages have this Message-ID (diff)
From: Linus Walleij <linus.walleij@linaro.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Alistair Strachan <astrachan@google.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Stefan Hajnoczi <stefanha@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Viresh Kumar <vireshk@kernel.org>,
virtualization@lists.linux-foundation.org,
linux-kernel <linux-kernel@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
"Enrico Weigelt, metux IT consult" <info@metux.net>,
Bill Mills <bill.mills@linaro.org>,
stratos-dev@op-lists.linaro.org
Subject: Re: [PATCH V3 1/3] gpio: Add virtio-gpio driver
Date: Tue, 15 Jun 2021 22:03:21 +0200 [thread overview]
Message-ID: <CACRpkdbyybnxP9p3Jh2TbJMhK+kfLyed-YyrZq9JbOqu1csmww@mail.gmail.com> (raw)
In-Reply-To: <20210615111551.7tcz7teqp4olhodf@vireshk-i7>
On Tue, Jun 15, 2021 at 1:15 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> I am now wondering how interrupts can be made to work here. Do you
> have anything in mind for that ?
The aggregator does not aggregate interrupts only lines for now.
> GPIO sysfs already supports interrupts, (...)
I hope that doesn't make you tempted to use sysfs to get interrupts,
those are awful, they use sysfs_notify_dirent() which means that
if two IRQs happen in fast succession you will miss one of them
and think it was only one.
The GPIO character device supports low latency events forwarding
interrupts to userspace including QEMU & similar, timestamps the
events as close in time as possible to when they actually happen
(which is necessary for any kind of industrial control) and will never
miss an event if the hardware can register it. See:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/gpio/gpio-event-mon.c
Yours,
Linus Walleij
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2021-06-15 20:03 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 12:09 [PATCH V3 0/3] gpio: Add virtio based driver Viresh Kumar
2021-06-10 12:09 ` Viresh Kumar
2021-06-10 12:16 ` [PATCH V3 1/3] gpio: Add virtio-gpio driver Viresh Kumar
2021-06-10 12:16 ` Viresh Kumar
2021-06-10 13:22 ` Arnd Bergmann
2021-06-10 16:00 ` Enrico Weigelt, metux IT consult
[not found] ` <01000179f6a7715c-cd106846-7770-4088-bb7c-a696bfcbf83e-000000@email.amazonses.com>
2021-06-10 17:03 ` [Stratos-dev] " Jean-Philippe Brucker
2021-06-10 17:03 ` Jean-Philippe Brucker
2021-06-10 19:41 ` Arnd Bergmann
2021-06-14 10:21 ` Viresh Kumar
2021-06-14 10:21 ` Viresh Kumar
2021-06-14 12:31 ` Arnd Bergmann
2021-06-14 12:49 ` Vincent Guittot
[not found] ` <0100017a0a9264cc-57668c56-fdbf-412a-9f82-9bf95f5c653e-000000@email.amazonses.com>
2021-06-14 12:58 ` [Stratos-dev] " Arnd Bergmann
2021-06-14 13:24 ` Vincent Guittot
2021-06-14 20:54 ` Arnd Bergmann
2021-06-15 7:30 ` Vincent Guittot
2021-06-10 15:54 ` Enrico Weigelt, metux IT consult
2021-06-10 16:57 ` Viresh Kumar
2021-06-10 16:57 ` Viresh Kumar
2021-06-10 20:46 ` Linus Walleij
2021-06-10 20:46 ` Linus Walleij
2021-06-11 3:56 ` Viresh Kumar
2021-06-11 3:56 ` Viresh Kumar
2021-06-11 7:42 ` Geert Uytterhoeven
2021-06-11 7:42 ` Geert Uytterhoeven
2021-06-11 8:01 ` Viresh Kumar
2021-06-11 8:01 ` Viresh Kumar
2021-06-11 8:22 ` Geert Uytterhoeven
2021-06-11 8:22 ` Geert Uytterhoeven
2021-06-15 11:15 ` Viresh Kumar
2021-06-15 11:15 ` Viresh Kumar
2021-06-15 11:37 ` Geert Uytterhoeven
2021-06-15 11:37 ` Geert Uytterhoeven
2021-06-15 20:03 ` Linus Walleij [this message]
2021-06-15 20:03 ` Linus Walleij
2021-06-16 1:45 ` Viresh Kumar
2021-06-16 1:45 ` Viresh Kumar
2021-06-14 8:07 ` Enrico Weigelt, metux IT consult
2021-06-14 8:12 ` Andy Shevchenko
2021-06-14 8:12 ` Andy Shevchenko
2021-06-14 9:14 ` Viresh Kumar
2021-06-14 9:14 ` Viresh Kumar
2021-06-14 9:17 ` Enrico Weigelt, metux IT consult
2021-06-14 9:52 ` Viresh Kumar
2021-06-14 9:52 ` Viresh Kumar
2021-06-14 9:12 ` Viresh Kumar
2021-06-14 9:12 ` Viresh Kumar
2021-06-14 9:29 ` Enrico Weigelt, metux IT consult
2021-06-14 8:03 ` Enrico Weigelt, metux IT consult
2021-06-14 9:24 ` Viresh Kumar
2021-06-14 9:24 ` Viresh Kumar
2021-06-16 3:30 ` Bjorn Andersson
2021-06-16 3:30 ` Bjorn Andersson
2021-06-16 15:52 ` Enrico Weigelt, metux IT consult
2021-06-18 9:13 ` Linus Walleij
2021-06-18 9:13 ` Linus Walleij
2021-06-21 17:25 ` Bjorn Andersson
2021-06-21 17:25 ` Bjorn Andersson
2021-06-10 12:16 ` [PATCH V3 2/3] gpio: virtio: Add IRQ support Viresh Kumar
2021-06-10 12:16 ` Viresh Kumar
2021-06-10 21:30 ` Linus Walleij
2021-06-10 21:30 ` Linus Walleij
2021-06-14 7:08 ` Viresh Kumar
2021-06-14 7:08 ` Viresh Kumar
2021-06-10 12:16 ` [PATCH V3 3/3] MAINTAINERS: Add entry for Virtio-gpio Viresh Kumar
[not found] ` <01000179f5da7763-2ea817c6-e176-423a-952e-de02443f71e2-000000@email.amazonses.com>
2021-06-10 17:40 ` [PATCH V3 1/3] gpio: Add virtio-gpio driver Jean-Philippe Brucker
2021-06-10 17:40 ` Jean-Philippe Brucker
2021-06-11 3:39 ` Viresh Kumar
2021-06-11 3:39 ` Viresh Kumar
[not found] ` <01000179f9276678-ae2bb25f-4c0c-4176-b906-650c585b9753-000000@email.amazonses.com>
2021-06-11 8:34 ` [Stratos-dev] " Arnd Bergmann
2021-06-14 5:26 ` Viresh Kumar
2021-06-14 5:26 ` Viresh Kumar
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=CACRpkdbyybnxP9p3Jh2TbJMhK+kfLyed-YyrZq9JbOqu1csmww@mail.gmail.com \
--to=linus.walleij@linaro.org \
--cc=alex.bennee@linaro.org \
--cc=astrachan@google.com \
--cc=bgolaszewski@baylibre.com \
--cc=bill.mills@linaro.org \
--cc=bjorn.andersson@linaro.org \
--cc=geert@linux-m68k.org \
--cc=info@metux.net \
--cc=jasowang@redhat.com \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mst@redhat.com \
--cc=sgarzare@redhat.com \
--cc=stefanha@redhat.com \
--cc=stratos-dev@op-lists.linaro.org \
--cc=vincent.guittot@linaro.org \
--cc=viresh.kumar@linaro.org \
--cc=vireshk@kernel.org \
--cc=virtualization@lists.linux-foundation.org \
--cc=wsa+renesas@sang-engineering.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.