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

From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	Frieder Schrempf <frieder.schrempf@kontron.de>,
	Richard Genoud <richard.genoud@gmail.com>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	NXP Linux Team <linux-imx@nxp.com>,
	linux-serial@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-renesas-soc@vger.kernel.org,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Ludovic Desroches <ludovic.desroches@microchip.com>
Subject: Re: [PATCH 1/3] serial: atmel: Don't check for mctrl_gpio_to_gpiod() returning error
Date: Wed, 14 Aug 2019 11:35:58 +0200	[thread overview]
Message-ID: <20190814093558.xlx5ck54dw2dgb6k@pengutronix.de> (raw)
In-Reply-To: <20190814092924.13857-2-geert+renesas@glider.be>

Hello,

[adding the Atmel guys to Cc]

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?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |