Re: [PATCH 4/4] tty/serial: sh-sci: remove uneeded IS_ERR_OR_NULL calls

[Linus Walleij]

On Mon, Mar 6, 2017 at 11:02 AM, Uwe Kleine-KÃnig
<u.kleine-koenig@xxxxxxxxxxxxxx> wrote:
> On Mon, Mar 06, 2017 at 10:53:27AM +0100, Geert Uytterhoeven wrote:
>> On Mon, Mar 6, 2017 at 10:30 AM, Uwe Kleine-KÃnig

>> > I wouldn't want to code this in each driver (something like:
>> >
>> >         if (IS_ENABLED(GPIOLIB) || device_is_instantiated_by_dt(dev) || device_is_instantiated_by_acpi(dev))
>> >                 gpios = mctrl_gpio_init(...);
>> >         else
>> >                 gpios = NULL;
>> >
>> > ). Putting this into GPIOLIB is the right approach, and so this is
>> > another argument for HALFGPIOLIB. This would fix mctrl_gpio_init en
>> > passant.
>>
>> Do we have platforms where DT=y || ACPI=y, but GPIOLIB=n?
>> Ah, x86 ;-)
>
> Yeah, and I think rm -r arch/x86 won't be acceptable :-) I assume you
> can also configure some arm or powerpc systems without GPIOLIB.
>
>> Anyway, for sh-sci.c, platforms either have DT and GPIOLIB, or they do not
>> need mctrl-gpio.
>
> So we're in agreement now that HALFGPIOLIB is the way to go?
> Linus, what do you think?

OK modem lines over GPIO.

So the problem is that GPIOLIB is needed (obviously) for mctrl_gpio_init() to
work properly, and then there are some stubs in
drivers/tty/serial/serial_mctrl_gpio.h
for !GPIOLIB.

And this whole discussion is all about that !GPIOLIB case really,
whether DT, ACPI, SFI or board files machine data is used doesn't
really matter.

We're talking about:

> git grep mctrl_gpio_init
drivers/tty/serial/atmel_serial.c:      atmel_port->gpios =
mctrl_gpio_init(&atmel_port->uart, 0);
drivers/tty/serial/clps711x.c:  s->gpios =
mctrl_gpio_init_noauto(&pdev->dev, 0);
drivers/tty/serial/etraxfs-uart.c:      up->gpios =
mctrl_gpio_init_noauto(&pdev->dev, 0);
drivers/tty/serial/imx.c:       sport->gpios = mctrl_gpio_init(&sport->port, 0);
drivers/tty/serial/mxs-auart.c: s->gpios = mctrl_gpio_init_noauto(dev, 0);
drivers/tty/serial/sh-sci.c:    sciport->gpios =
mctrl_gpio_init(&sciport->port, 0);

Atmel, ARM, ETRAX, ARM, ARM, Super-H, all have GPIOLIB.
Right now no x86, correct?

They actually all even do things like this in Kconfig:

config SERIAL_ATMEL
(...)
        select SERIAL_MCTRL_GPIO if GPIOLIB

What stops us from removing all the stubs in
drivers/tty/serial/serial_mctrl_gpio.h
and just make SERIAL_MCTRL_GPIO depends on GPIOLIB?