On Fri Jun 19, 2026 at 11:08 PM CEST, Linus Walleij wrote:
> On Mon, Jun 8, 2026 at 4:41 PM Michael Walle <mwalle@kernel.org> wrote:
>
>> >>> Without an accessor like gpio_regmap_get_gpiochip(), we cannot retrieve the
>> >>> gpio_chip instantiated inside gpio-regmap.c to fulfill these requirements in our
>> >>> map() function.
>>
>> Why is gpiochip_irq_reqres() called in the first place? Isn't that
>> only called if the irq handling is set up via gc->irq.chip and not
>> via gpiochip_irqchip_add_domain() like in gpio-regmap?
>
> Not really, the gpiochip_irq_reqres() is called to mark that a
> GPIO line is used for IRQ, so the gpiolib cannot turn this
> GPIO into an output line, gpiod_direction_out() will fail
> on lines used for IRQ. So it's a failsafe.
>
> You can live without it of course, but then you don't get
> this failsafe.

Thanks for the explanation! So did I make a mistake years ago by
adding the gpiochip_irqchip_add_domain(), see commit 6a45b0e2589f
("gpiolib: Introduce gpiochip_irqchip_add_domain()")

As Yu-Chun found, gpiochip_irq_reqres() expect the irq chip data
to be a gpio_chip, which isn't the case (in general) for an
externally allocated domain, is it?

-michael