Re: [PATCH 1/3] serial: atmel: Don't check for mctrl_gpio_to_gpiod() returning error

From: Richard Genoud <richard.genoud@gmail.com>
To: "Geert Uytterhoeven" <geert@linux-m68k.org>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
	Richard Genoud <richard.genoud@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Frieder Schrempf <frieder.schrempf@kontron.de>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	Ludovic Desroches <ludovic.desroches@microchip.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Fabio Estevam <festevam@gmail.com>, Jiri Slaby <jslaby@suse.com>,
	Shawn Guo <shawnguo@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/3] serial: atmel: Don't check for mctrl_gpio_to_gpiod() returning error
Date: Tue, 20 Aug 2019 17:11:56 +0200	[thread overview]
Message-ID: <fc23b475-db5f-a311-5c7e-9fac15da3684@gmail.com> (raw)
In-Reply-To: <CAMuHMdWNj-H9B8E9=NeCgLracBuJODfPyBYJERh=vt4oNFUkGw@mail.gmail.com>

Hi,
Le 14/08/2019 à 12:20, Geert Uytterhoeven a écrit :
> Hi Uwe,
> 
> On Wed, Aug 14, 2019 at 11:36 AM Uwe Kleine-König
> <u.kleine-koenig@pengutronix.de> wrote:
>> On Wed, Aug 14, 2019 at 11:29:22AM +0200, Geert Uytterhoeven wrote:
>>> Since commit 1d267ea6539f2663 ("serial: mctrl-gpio: simplify init
>>> routine"), mctrl_gpio_init() returns failure if the assignment to any
>>> member of the gpio array results in an error pointer.
>>> Since commit c359522194593815 ("serial: mctrl_gpio: Avoid probe failures
>>> in case of missing gpiolib"), mctrl_gpio_to_gpiod() returns NULL in the
>>> !CONFIG_GPIOLIB case.
>>> Hence there is no longer a need to check for mctrl_gpio_to_gpiod()
>>> returning an error value.  A simple NULL check is sufficient.
>>>
>>> This follows the spirit of commit 445df7ff3fd1a0a9 ("serial: mctrl-gpio:
>>> drop usages of IS_ERR_OR_NULL") in the mctrl-gpio core.
>>>
>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>>> ---
>>>  drivers/tty/serial/atmel_serial.c | 12 ++++--------
>>>  1 file changed, 4 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
>>> index 19a85d6fe3d20541..e9620a81166b7dc1 100644
>>> --- a/drivers/tty/serial/atmel_serial.c
>>> +++ b/drivers/tty/serial/atmel_serial.c
>>> @@ -303,32 +303,28 @@ static unsigned int atmel_get_lines_status(struct uart_port *port)
>>>
>>>       mctrl_gpio_get(atmel_port->gpios, &ret);
>>>
>>> -     if (!IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(atmel_port->gpios,
>>> -                                             UART_GPIO_CTS))) {
>>> +     if (mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_CTS)) {
>>>               if (ret & TIOCM_CTS)
>>>                       status &= ~ATMEL_US_CTS;
>>>               else
>>>                       status |= ATMEL_US_CTS;
>>>       }
>>
>> The change is fine, but it seems the atmel driver doesn't use mctrl_gpio
>> as expected (at least as expected by me). IMHO driving the hardware
>> function of the CTS pin shouldn't be conditional on the presence of a
>> cts-gpio. Is there a reason not to just drop the if completely?
> 
> The above code returns the hardware status if CTS is not a GPIO, and
> returns (overrides with) the GPIO status if CTS is a GPIO.
> Isn't that correct, or am I missing something?
Yes, that's correct.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel