Messages in this thread | | | Date | Mon, 6 Mar 2017 10:30:43 +0100 | From | Uwe Kleine-König <> | Subject | Re: [PATCH 4/4] tty/serial: sh-sci: remove uneeded IS_ERR_OR_NULL calls |
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Hello Geert,
On Mon, Mar 06, 2017 at 10:09:50AM +0100, Geert Uytterhoeven wrote: > On Mon, Mar 6, 2017 at 9:58 AM, Uwe Kleine-König > <u.kleine-koenig@pengutronix.de> wrote: > > On Mon, Mar 06, 2017 at 09:49:39AM +0100, Geert Uytterhoeven wrote: > >> > Given that mctrl-gpio can be useful on legacy platforms, a device could > >> > silently run without cts-gpio even there. > >> > >> On platforms were CONFIG_GPIOLIB=n, this is not true, so the issue is moot. > >> > >> All serial drivers using (optional) mctrl-gpio have this in Kconfig: > >> > >> select SERIAL_MCTRL_GPIO if GPIOLIB > >> > >> So they will use mctrl-gpio when GPIOLIB is enabled. > >> If GPIOPLIB is disabled, no flow control GPIOs are expected, and the > >> driver should not break that case. > > > > So it all boils down to the question: Is GPIOLIB=n enough to assume no > > gpio is needed? > > > > I'd say it is not. > > How does the platform register these GPIOs when GPIOPLIB is not enabled by > the platform, and gpiod_add_lookup_table() is thus not available?
Obviously the platformcode cannot. In this case you could argue that platformcode shouldn't register the device if a gpio is necessary. But this reasoning doesn't work for (DT=y || ACPI=y) && GPIOLIB=n.
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.
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
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