Re: [RFC v2 0/2] gpio: Support for shared GPIO lines on boards

[Linus Walleij]

On Mon, Nov 4, 2019 at 8:11 PM Rob Herring <robh+dt@xxxxxxxxxx> wrote:
> [Peter]
> > The device needs the RST line to be high, otherwise it is not
> > accessible. If it does not have reset control how can we make sure that
> > the GPIO line is in correct state?
>
> Just like the reset code, drivers register their use of the reset and
> the core tracks users and prevents resetting when not safe. Maybe the
> reset subsystem needs to learn about GPIO resets. (...)

I agree. Certainly the reset subsystem can do what the regulator
subsystem is already doing: request the GPIO line nonexclusive
and handle any reference counting and/or quirks that are needed
in a hypothetical drivers/reset/reset-gpio.c driver.

There is no such driver today, just a "reset" driver in
drivers/power/reset that resets the whole system.

But I see no problem in creating a proper reset driver in drivers/reset
to handle a few peripherals with a shared GPIO reset line.

Yours,
Linus Walleij