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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Tue, 28 Jul 2020 10:09:33 +0200
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Subject: Re: [PATCH V2 1/4] gpio: mxc: Support module build
To:     Arnd Bergmann <arnd@arndb.de>
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        Russell King - ARM Linux <linux@armlinux.org.uk>,
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On Mon, Jul 27, 2020 at 1:57 PM Arnd Bergmann <arnd@arndb.de> wrote:

> Overall, my feeling is that making sure all drivers that depend on the pinctrl
> driver can deal with deferred probing is a prerequisite before this can be
> made a loadable module itself (same for clk, irqchip, etc drivers that others
> may rely on).
>
> I understand that your primary motivation is to fit into Google's GKI framework,
> but I think that doing the conversion only partially would neither serve to
> improve the kernel nor actually meet the GKI requirements.

This has been my worry as well when it comes to these GKI-initiated
patches that are flying right now.

> Most pinctrl drivers are currently always built-in to work around the
> load order dependencies. This of course is a bit of a hack and we'd be
> better off if all drivers managed to avoid the dependencies, but this
> can also require a lot of work.

Several people have argued that it is reasonable to cut corners to
achieve the "greater good" of GKI.

I try to handle it on a "does the kernel look better after than
before" basis, while pushing gently for at least trying to
properly modularize the whole thing. It can become pretty hard
to test I think. If it is things like GPIO expanders on I2C
that can be used by several SoCs I would be more hard on
this, on a single SoC not as much.

One discussion thread got inflamed because of ARM vs x86
discussions "x86 is better modularized" which is something I want
to avoid, it is easy to be modularized when your irqs, clocks,
regulators and pins are handled by the BIOS. This is a SoC
problem and x86 SoCs with no BIOS, RISCV, ARM and whatever
doesn't have a fix-it-all-BIOS have this problem. :/

Yours,
Linus Walleij