Re: [PATCH 1/6 v2] gpio: Add support for hierarchical IRQ domains

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Fri, Aug 23, 2019 at 11:12 AM Marc Zyngier <marc.zyngier@xxxxxxx> wrote:

> > We should be encouraged to operate on IRQ descriptors rather
> > than IRQ numbers when doing this kind of deep core work,
> > right?
>
> Certainly, I'd like to gradually move over from the IRQ number to an
> irq_desc. In interrupt-heavy contexts, this ends up being quite time
> consuming. I have an old patch series somewhere changing irq domains to
> use irq_descs internally instead of IRQ numbers, which I should maybe
> revive.

We currently interact most heavily with the irqchip by way of
mapping GPIO lines to the corresponding IRQs, so I suppose
the existing

int gpiod_to_irq(struct gpio_desc *desc);

Need a corresponding

struct irq_desc *gpiod_to_irq_desc(struct gpio_desc *desc);

at some point, and then we can start to de-pollute the kernel
from this for all drivers using the modern GPIO descriptor
API. It's a big task but can certainly be done with some
help.

On the driver back-end we are in surprisingly good shape
thanks to all the abstractions provided for dealing with IRQ
chip drivers.

Yours,
Linus Walleij