Re: [PATCH v1 4/8] pinctrl: add NXP MC33978/MC34978 pinctrl driver

[Linus Walleij]

On Fri, Feb 27, 2026 at 11:58 AM Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote:

> > The driver needs to report the *physical* level on the line. Then the
> > lines need to be flagged with GPIO_ACTIVE_LOW or GPIO_ACTIVE_HIGH
> > on the consumers in the device tree.
>
> Returning the physical level is actually exactly what this code is
> trying to do. I need to rewrite the comment :)

Aha OK I'm not very smart at times...

> The issue is that the MC33978 hardware does not report the physical
> voltage level on the pin. As per section 9.10.27 (Read switch status) of
> the datasheet: "A Logic [1] means the switch is closed while a Logic [0]
> is an open switch."
>
> Because it only reports this abstract "contact status", I have to
> translate it back to the actual physical voltage level (1 = High, 0 =
> Low) based on the pin's current configuration:
>
> In Switch-to-Ground (SG) mode: the status bit stays 0 when the physical
> voltage on the line is High (open), and reports 1 when the physical
> voltage is Low (shorted to ground).
> In Switch-to-Battery (SB) mode: the exact opposite happens.

Fair enough, as long as we have a (possibly verbose...) explanation
about what is going on in the binding document I think the
proper driver behaviour will come out as obvious in the end.

Yours,
Linus Walleij