Re: [PATCH 4/9] pinctrl: meson: allow gpio to request irq

[Linus Walleij]

On Tue, Oct 25, 2016 at 4:47 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
> On 25/10/16 15:22, Jerome Brunet wrote:

>> There is a few problems to guarantee that gpio == hwirq.
>> 1. We have 2 instances of pinctrl, to guarantee that the linux gpio
>> number == hwirq, we would have to guarantee the order in which they are
>> probed. At least this my understanding
>
> Maybe I wasn't clear enough, and my use of gpio is probably wrong. So
> Linux has a gpio number, which is obviously an abstract number (just
> like the Linux irq number). But the pad number, in the context of given
> SoC, is constant. So we have:
>
>         pad->gpio
>         hwirq->irq
>
> Why can't you have pad == hwirq, always? This is already what you have
> in the irqchip driver. This would simplify a lot of things.

My thought as well.

We usually refer to the local numberspace on the GPIO controller
as "offsets", so line offsets 0...31 on a gpiochip with 31 lines.

The ngpio in struct gpio_chip is the number of lines on that controller,
and should nominally map 1:1 to hwirq sources.

Yours,
Linus Walleij