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

[Wolfram Sang]

Hi Linus,

giving some details about the HW until Herve can return to this topic.

> Are these IRQ lines ever muxed for anything else than
> GPIO? In that case go ahead with this solution, I guess.
> But the title of your patch seems to suggest it is
> only used by GPIO.

True, it only muxes 96 GPIOs to the 8 available irqs.

> If it is only used for GPIO, why make it a separate
> driver instead of just putting the muxing into the
> GPIO driver?

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.

I am just stating where this comes from. I haven't looked into the
details of your suggestion. It may or may not make sense to add this to
the Synopsis driver with a dedicated compatible for RZ/N1D. I'll leave
this for Herve, though.

Happy hacking,

   Wolfram

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