Re: [PATCH v4 7/8] soc: renesas: Add support for Renesas RZ/N1 GPIO Interrupt Multiplexer

[Herve Codina <herve.codina@bootlin.com>]

Hi Linus, Wolfram,

On Tue, 14 Oct 2025 22:13:50 +0200
Linus Walleij <linus.walleij@linaro.org> wrote:

> On Tue, Oct 14, 2025 at 4:30 PM Wolfram Sang
> <wsa+renesas@sang-engineering.com> wrote:
> 
> > Because the HW design kind of suggests it, I'd think. The GPIO
> > controller is a standard Synopsis one ("snps,dw-apb-gpio") without any
> > extras. The GPIOMUX (which is extra) is according to the docs part of
> > the system controller with a dedicated set of registers. Luckily,
> > self-contained and not mangled with other functionality.  
> 
> Aha I see. If this is so tightly coupled with the Synopsis
> designware GPIO then it should be mentioned in the commit
> I guess. Also:
> 
> config RZN1_IRQMUX
>        bool "Renesas RZ/N1 GPIO IRQ multiplexer support" if COMPILE_TEST
> 
> +      depends on GPIO_DWAPB || COMPILE_TEST
> 
> ?
> 
> I understand that it is convenient to make this a separate driver.
> 
> I'm not sure it is the right thing to do, but it's no a hill I want to
> die on so if everyone else thinks I'm wrong, I can just shut up
> about it, it's not like this driver is a big obstacle or anything.
> 
> Yours,
> Linus Walleij

I don't think the mux should depends on GPIO_DWAPB (the gpio controller).

Also, several gpio controller instances are connected to the mux.

The 96 GPIOs connected to the mux come from 3 GPIO controller instances (32
gpios per instance). I don't think it makes sense to have the mux handled by
the gpio driver itself. It could have make sense if 3 muxes were available,
one per gpio controller but this is not the case.

As Wolfram said, the mux is an hardware component really outside of the
GPIO controller IPs.

Best regards,
Hervé