Re: [PATCH v3] gpio: interrupt consistency check for OF GPIO IRQs

Linus Walleij
2013-09-03T12:43:57Z

On Fri, Aug 30, 2013 at 9:55 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
> On 08/29/2013 06:24 PM, Javier Martinez Canillas wrote:
> ...
>> We have been trying to solve this issue for a few months by now and Linus'
>> approach seems to be the most sensible solution to me.
>>
>> Drivers that request an IRQ and assume that platform code will request and setup
>> the GPIO have been broken since the boards using these drivers were migrated to
>> DT (e.g: smsc911x on OMAP2+ boards).
>
> That's only true if the driver for the GPIO controller is buggy.
> Whatever request_irq() maps down to in the GPIO/IRQ controller driver
> simply needs to set up the pin as an interrupt input, then it doesn't
> matter which order the driver does things.

As mentioned it can't do that, because doing that creates a
restriction on which order the driver does things...

But you mentioned that you wanted an API that would account
for the case where the *same driver* requested the same resource
(a GPIO line) to be used for both IRQ and GPIO, through two
different calls.

I would be happy to see how we could do that, preferably in a
generic way.

Since the gpio_request() does not contain the signature of the
calling driver I don't see how we could do this without refactoring
the whole world.

In that case it would probably be easiest to
*first* proceed to complete Alexandre's suggested refactorings for
GPIO descriptors, which tie down GPIOs to be requested like
clocks and regulators and thus tied to a device, so we can from
there proceed to implement such a conditional request,
as we will then have the required information in the GPIO
subsystem.

Yours,
Linus Walleij