Re: [PATCH v3 2/7] gpio: regmap: add gpio_regmap_get_gpiochip() accessor

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Wed, Jul 1, 2026 at 11:44 AM Michael Walle <mwalle@kernel.org> wrote:
> 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?

So the whole issue comes from the fact that the IRQ chip is not marked
as immutable. For immutable IRQ chips (which all GPIO provides should
have) there is no such issue to begin with, id est there is no
gpiochip_irq_reqres() callback assigned (and respective _relres).


--
With Best Regards,
Andy Shevchenko