Subject: [PATCH 3/5] gpio/omap: Add DT support to GPIO driver

From: [email-masked] (Stephen Warren)
Date: Wed, 27 Feb 2013 10:50:57 -0700

On 02/26/2013 08:57 PM, Javier Martinez Canillas wrote:
> On Wed, Feb 27, 2013 at 2:07 AM, Jon Hunter <[email-masked]> wrote:
>>
>> On 02/26/2013 06:13 PM, Stephen Warren wrote:
>>> On 02/26/2013 04:45 PM, Jon Hunter wrote:
...
>>>> One issue I see is that by not calling gpio_request, then potentially
>>>> you could have someone request a gpio via gpio_request() and someone
>>>> trying to use it as an interrupt source via request_irq(). Now obviously
>>>> that represents a bug because there is only one physical gpio, but I
>>>> gather it is something we need to protect against.
>>>
>>> I'm not sure it's really that much of an issue, but presumably the
>>> solution is for a combined GPIO+IRQ driver to simply call gpio_request
>>> internally from within some irq_chip function. It looks like struct
>>> irq_chip doesn't have a request/free, but perhaps they could be added to
>>> solve this?
>>
>> Yes I was wondering if we could do something like that. That would work,
>> may be that's what we should propose.
> 
> Something like that would definitely solve the GPIO request issue but
> we still have the issue that the current OMAP GPIO controller binding
> does not support #interrupt-cells = <2>.

The binding documentation in
Documentation/devicetree/bindings/gpio/gpio-omap.txt indicates that it
does. If this doesn't work in practice, it's a driver bug that can
presumably be easily fixed. And no need to change any ABI definitions:-)

BTW, I notice in that binding document that the description of the two
cells for #interrupt-cells is actually part of the description of the
"interrupt-controller" property; it should be moved up one line really.