From mboxrd@z Thu Jan 1 00:00:00 1970 From: geert@linux-m68k.org (Geert Uytterhoeven) Date: Mon, 6 Mar 2017 10:53:27 +0100 Subject: [PATCH 4/4] tty/serial: sh-sci: remove uneeded IS_ERR_OR_NULL calls In-Reply-To: <20170306093043.ay4dz3ehp3aakwxh@pengutronix.de> References: <20170303142201.16452-1-richard.genoud@gmail.com> <20170303191248.wlwjri55ip2x5pgg@pengutronix.de> <20170303194414.n76tr3oa2mlrzjre@pengutronix.de> <20170304174819.esxhwwbsxzuq3vyc@pengutronix.de> <20170306085842.yijkfpqi3adcedmm@pengutronix.de> <20170306093043.ay4dz3ehp3aakwxh@pengutronix.de> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Uwe, On Mon, Mar 6, 2017 at 10:30 AM, Uwe Kleine-K?nig wrote: > On Mon, Mar 06, 2017 at 10:09:50AM +0100, Geert Uytterhoeven wrote: >> On Mon, Mar 6, 2017 at 9:58 AM, Uwe Kleine-K?nig >> 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. Do we have platforms where DT=y || ACPI=y, but GPIOLIB=n? Ah, x86 ;-) Anyway, for sh-sci.c, platforms either have DT and GPIOLIB, or they do not need mctrl-gpio. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds