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

[Dmitry Eremin-Solenikov]

On 09/01/2014 04:06 PM, Mark Brown wrote:
> On Mon, Sep 01, 2014 at 03:59:34PM +0400, Dmitry Eremin-Solenikov wrote:
> > On 09/01/2014 02:15 PM, Mark Brown wrote:
>
> > > 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.
>
> Please consider my point about making users instantly buggy - it's not
> practical to introduce a new field into existing platform data which
> needs initialization.  Disallowing the use of 0 as a GPIO seems more
> practical here (in that it's something the platform can control with
> more reliable coordination).

I think that this makes other users buggy - those, whose platforms use 
GPIO numbering starting from 0. IMX platform does. legacy platforms do.

Consider NO_IRQ which is still defined to -1 on ARM platforms. If a 
device does not have a connected IRQ, it has to explicitly specify -1 
instead of specifying logical default 0. Is it so? What is so different 
with GPIOs and regulators?

--
With best wishes
Dmitry
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