Re: [PATCH V2] media: i2c: Add ADV761X support

[Lars-Peter Clausen <lars@metafoo.de>]

On 11/29/2013 08:52 PM, Linus Walleij wrote:
> On Fri, Nov 29, 2013 at 2:48 PM, Lars-Peter Clausen <lars@metafoo.de> wrote:
>> On 11/29/2013 02:42 PM, Linus Walleij wrote:
>>> On Fri, Nov 29, 2013 at 11:45 AM, Lars-Peter Clausen <lars@metafoo.de> wrote:
>>>>
>>>> As far as I understand it this already works more or less with the driver.
>>>> The problem is that the IRQ numbers are dynamically allocated, while the
>>>> GPIO numbers apparently are not. So the board code knows the the GPIO number
>>>> at compile time and can pass this to the diver which then does a gpio_to_irq
>>>> to lookup the IRQ number. This of course isn't really a problem with
>>>> devicetree, but only with platform board code.
>>>
>>> This has been solved *also* for platform board code by the new, fresh
>>> GPIO descriptor mechanism, see Documentation/gpio/*
>>> in Torvalds' git HEAD.
>>
>> This works when the GPIO numbers are dynamically allocated (which are static
>> in this case), but not for IRQ numbers.
> 
> Sorry I don't get what you're after here. I'm not the subsystem
> maintainer for IRQ chips ...

I'm trying to explain, that the problem is not about GPIO number lookup, but
rather about IRQ number lookup :)

> 
> In the DT boot path for platform or AMBA devices the IRQs
> are automatically resolved to resources and passed with the
> device so that is certainly not the problem, right?

Yep, what I said earlier, this is a problem that's solved by using DT.

> 
> I guess you may be referring to the problem of instatiating
> a dynamic IRQ chip in *board code* and then passing the
> obtained dynamic IRQ numbers as resources to the
> devices also created in a board file?
> 

Yes.

> That would be like you're asking for a function that would
> return the base of an irq_chip, that needs to be discussed
> with the irq maintainers, so not much I can say, but maybe
> I misunderstood this?

I my opinion the best solution for this problem is to have the same lookup
mechanism we've had for clocks, regulators, etc and now also GPIOs.

- Lars