From: Arnd Bergmann <arnd@arndb.de>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Markus Pargmann <mpa@pengutronix.de>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
Johan Hovold <johan@kernel.org>,
Alexandre Courbot <acourbot@nvidia.com>,
Michael Welling <mwelling@ieee.org>,
Mark Brown <broonie@kernel.org>,
Amit Kucheria <amit.kucheria@linaro.org>
Subject: Re: [PATCH 0/6] GPIO character device skeleton
Date: Fri, 30 Oct 2015 23:54:48 +0100 [thread overview]
Message-ID: <3839397.mYWtgokiUO@wuerfel> (raw)
In-Reply-To: <CACRpkdYiQ=eQpUNspRH27x=9soExn-Mx5Rhc7USqAk7g5DNG_A@mail.gmail.com>
On Friday 30 October 2015 15:43:18 Linus Walleij wrote:
> On Sat, Oct 24, 2015 at 8:42 PM, Markus Pargmann <mpa@pengutronix.de> wrote:
>
> > What happens if we have two I2C gpio expanders with the same I2C
> > addresses connected to different I2C busses? If I see this correctly
> > they would both show up with the same name. Is there an easy and
> > race-free way to see which GPIO chip is connected to which I2C bus?
>
> My spontaneous question is: how does ethernet interfaces or whatever
> handle this nowadays to get unique device names?
>
> Currently we are probe-order dependent. It would be good to fix
> the plug-order business from day 1 but how?
ethernet devices are in their own namespace but can get renamed according
to distro-specific policy. A common method is to keep a record of all
mac addresses that were seen in a file in /etc (e.g.
/etc/udev/rules.d/70-persistent-net.rules) and rename them to whatever
they were previously known as when they show up with a different name.
For character devices, udev has a complex set of (user-overridable) rules
to derive one or more stable name(s) from the sysfs attributes.
Arnd
next prev parent reply other threads:[~2015-10-30 22:54 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-22 8:32 [PATCH 0/6] GPIO character device skeleton Linus Walleij
2015-10-22 8:32 ` [PATCH 1/6] gpio: make the gpiochip a real device Linus Walleij
2015-10-24 18:09 ` Markus Pargmann
2015-10-25 7:06 ` Alexandre Courbot
2015-10-26 2:12 ` Mark Brown
2015-11-03 21:20 ` Linus Walleij
2015-11-02 10:31 ` Johan Hovold
2015-11-02 12:25 ` Mark Brown
2015-11-02 12:43 ` Johan Hovold
2015-11-02 12:47 ` Mark Brown
2015-11-02 12:53 ` Johan Hovold
2015-11-02 13:06 ` Mark Brown
2015-11-02 13:14 ` Johan Hovold
2015-11-02 13:17 ` Mark Brown
2015-11-02 13:25 ` Johan Hovold
2015-11-03 21:24 ` Linus Walleij
2015-11-04 10:48 ` Linus Walleij
2015-11-05 9:44 ` Johan Hovold
2015-11-05 10:29 ` Mark Brown
2015-11-16 14:27 ` Linus Walleij
2015-12-03 14:04 ` Linus Walleij
2015-12-03 14:06 ` Linus Walleij
2015-12-03 21:26 ` Michael Welling
2015-12-04 22:31 ` Michael Welling
2015-12-11 17:58 ` Linus Walleij
2015-12-08 9:29 ` Johan Hovold
2015-12-11 18:06 ` Linus Walleij
2015-10-22 8:32 ` [PATCH 2/6] gpio: refer to gpio device in prints and debugfs Linus Walleij
2015-10-22 8:32 ` [PATCH 3/6] gpio: add a userspace chardev ABI for GPIOs Linus Walleij
2015-10-22 20:35 ` Michael Welling
2015-10-24 0:30 ` Greg Kroah-Hartman
2016-01-28 11:13 ` Linus Walleij
2015-10-26 1:34 ` Mark Brown
2016-01-27 10:05 ` Bamvor Zhang Jian
2016-01-28 11:14 ` Linus Walleij
2016-01-29 10:24 ` Bamvor Zhang Jian
2016-02-10 10:04 ` Linus Walleij
2015-10-22 8:32 ` [PATCH 4/6] tools/gpio: create GPIO tools Linus Walleij
2015-10-25 8:23 ` Alexandre Courbot
2015-10-22 8:32 ` [PATCH 5/6] gpio: add a userspace character device ABI Linus Walleij
2015-10-24 18:46 ` Markus Pargmann
2015-10-22 8:32 ` [PATCH 6/6] gpio: ABI: mark the sysfs ABI as obsolete Linus Walleij
2015-10-22 18:57 ` [PATCH 0/6] GPIO character device skeleton Michael Welling
2015-10-24 17:53 ` Markus Pargmann
2015-10-30 14:40 ` Linus Walleij
2015-11-02 10:00 ` Johan Hovold
2015-10-24 18:42 ` Markus Pargmann
2015-10-30 1:55 ` Alexandre Courbot
2015-10-30 19:48 ` Linus Walleij
2015-11-02 10:13 ` Johan Hovold
2015-11-03 7:23 ` Markus Pargmann
2015-11-03 12:06 ` Johan Hovold
2015-11-03 17:18 ` Linus Walleij
2015-11-04 19:44 ` Michael Welling
2015-11-05 9:40 ` Johan Hovold
2015-11-05 14:11 ` Linus Walleij
2015-11-06 10:21 ` Johan Hovold
2015-11-16 13:33 ` Linus Walleij
2015-11-03 17:05 ` Linus Walleij
2015-10-30 14:43 ` Linus Walleij
2015-10-30 22:54 ` Arnd Bergmann [this message]
2015-11-01 9:37 ` Linus Walleij
2015-11-02 10:16 ` Johan Hovold
2015-10-26 2:18 ` Mark Brown
2015-10-30 1:55 ` Alexandre Courbot
2015-10-30 19:47 ` Linus Walleij
2015-11-01 2:41 ` Mark Brown
2015-11-03 7:39 ` Markus Pargmann
2015-11-03 8:50 ` Mark Brown
2015-11-03 10:21 ` Amit Kucheria
2015-11-03 17:06 ` Linus Walleij
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