Re: [PATCH] regulator: core: GPIO #0 is a valid GPIO

From: Dmitry Eremin-Solenikov
Date: Mon Sep 01 2014 - 07:59:44 EST

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

"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");"


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
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