[PATCH v7 08/15] gpio: pl061: bind pinctrl by gpio request

[Haojian Zhuang]

On 22 January 2013 17:10, Linus Walleij <linus.walleij at linaro.org> wrote:
> On Mon, Jan 21, 2013 at 4:45 PM, Haojian Zhuang
> <haojian.zhuang at linaro.org> wrote:
>
>>> > +       pinctrl_request_gpio(gpio);
>>>
>>> Handling of error code?
>>>
>>> (Maybe I should add a __must_check on this function.)
>>>
>> My case is a little special. I don't want to check return value because some
>> gpio pins don't have pinmux registers in Hisilicon SoC.
>> So pinctrl_request_gpio() will always return error for these special pins in
>> Hisilicon SoC.
>>
>> If we must check the return value, maybe we need append a dummy pinctrl driver
>> for those special gpio pins. How do you think about it? Of course, I
>> need to evaluate
>> whether it's possible to implement.
>
> Hm. A dummy pinctrl back-end is not very elegant.
>
> It's better if the GPIO driver (gpio-pl061) keep track of the ranges that
> are connected to the pinctrl.
>
> If the ranges are encoded in the device tree (as I guess you want to do
> in this case) then the GPIO driver need to check these ranges to see if
> it uses a pinctrl backend. Magic behind-the-scenes is very hard to
> understand for people reading this code later.
>
> What about this:
>
> In gpiolib.c, function gpiochip_add_pin_range(), we save a copy of
> each range in &chip->pin_ranges.
>
> Add a function to gpiolib.c to check if a certain gpio is in the range
> of the current chip.
>
> Then use that:
>
> if (gpio_in_pinrange(gpio))
>     pinctrl_request_gpio(gpio);
>
> Yours,
> Linus Walleij

It seems better. I'll update it.

Regards
Haojian