[PATCH 3/3] gpio: sx150x: add dts support for sx150x driver

[Linus Walleij]

On Thu, Dec 4, 2014 at 1:12 PM, Barry Song <21cnbao at gmail.com> wrote:

> From: Wei Chen <Wei.Chen at csr.com>
>
> Current sx150x gpio expander driver doesn't support DT. Now we added DT support
> for this driver.
>
> Signed-off-by: Wei Chen <Wei.Chen at csr.com>
> Signed-off-by: Barry Song <Baohua.Song at csr.com>
(...)
> +-pullup_ena:A bit-mask which enables or disables the pull-up resistor
> +       for each IO line in the expander. = <0x0>;
> +
> +-pulldn_ena:A bit-mask which enables-or disables the pull-down resistor
> +       for each IO line in the expander.
> +
> +-open_drain_ena:A bit-mask which enables-or disables open-drain
> +       operation for each IO line in the expander.
> +
> +-polarity: A bit-mask which enables polarity inversion for each IO line
> +       in the expander.

I don't particularly like these properties.

This is basically pin control stuff.

I know that the driver was merged way before the pin control subsystem
existed and before I was maintainer of GPIO. So it has some tradition
behind it.

Still I would *really* prefer that it was at least described the way
pin controllers usually are, so we have the option of converting it
to pin control later.

The major difference if you check the pin control standard bindings,
is that instead of hammering down the config of different lines in
the controller, the config is tied to the consumers, as these are
the devices actually requiring that config.

I.e. it's not a property of the *controller* that a line is pulled down,
that is a property of whatever is connected to that line.

Maybe I'm overzealous so that this would require implenenting
a whole lot of pin control stuff and move the driver to drivers/pinctrl,
but I won't let it go without a discussion first.

Yours,
Linus Walleij