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

[Barry Song]

2015-01-09 18:02 GMT+08:00 Linus Walleij <linus.walleij at linaro.org>:
> 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.

my suggestion is we split this patch into two, the first one adds the
basic gpio dt support, then we consider the pin configuration issue.

>
> Yours,
> Linus Walleij
-barry