From: Dmitry Eremin-Solenikov <dmitry_eremin@mentor.com>
To: Mark Brown <broonie@kernel.org>, Dirk Behme <dirk.behme@de.bosch.com>
Cc: <linux-kernel@vger.kernel.org>,
Liam Girdwood <lgirdwood@gmail.com>,
Gokulkrishnan Nagarajan <Gokulkrishnan.Nagarajan@in.bosch.com>,
Grant Likely <grant.likely@secretlab.ca>,
Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH] regulator: core: GPIO #0 is a valid GPIO
Date: Mon, 1 Sep 2014 15:59:34 +0400 [thread overview]
Message-ID: <54045FA6.70602@mentor.com> (raw)
In-Reply-To: <20140901101512.GK29327@sirena.org.uk>
On 09/01/2014 02:15 PM, Mark Brown wrote:
> On Mon, Sep 01, 2014 at 09:46:54AM +0200, Dirk Behme wrote:
>> I wonder how this fits to
>
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/gpio/gpio-legacy.txt
>
>> "GPIOs are identified by unsigned integers in the range 0..MAX_INT"
>
>> "If you want to initialize a structure with an invalid GPIO number, use
>> some negative number (perhaps "-EINVAL");"
>
>> then?
>
> There's no practical way to deploy that without breaking users - as soon
> as you treat 0 as a valid GPIO you make all existing users relying on
> the natural behaviour of treating 0 as default instantly buggy which is
> not practical. Really the GPIO API is badly specified here.
>
Back in the time before DTS conversion started, the 0 was a correct GPIO
number. If somebody wanted to specify that no gpio is provided, he
provided -1 as an invalid number. I have the feeling that allowing users
to use 0 as 'no gpio' is a mistake. Or the API should be changed
to disallow GPIO 0 to exist at all.
--
With best wishes
Dmitry
next prev parent reply other threads:[~2014-09-01 11:59 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-29 18:19 [PATCH] regulator: core: GPIO #0 is a valid GPIO Dmitry Eremin-Solenikov
2014-08-29 19:01 ` Mark Brown
2014-09-01 7:46 ` Dirk Behme
2014-09-01 7:55 ` Geert Uytterhoeven
2014-09-01 10:15 ` Mark Brown
2014-09-01 11:59 ` Dmitry Eremin-Solenikov [this message]
2014-09-01 12:06 ` Mark Brown
2014-09-01 12:35 ` Dmitry Eremin-Solenikov
2014-09-01 12:49 ` Mark Brown
2014-09-03 9:04 ` Dmitry Eremin-Solenikov
2014-09-03 11:01 ` Mark Brown
2014-09-04 17:15 ` Linus Walleij
2014-09-04 17:19 ` Linus Walleij
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