linux-kernel - Re: [PATCH] serial: mctrl_gpio: Avoid probe failures in case of missing gpiolib

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Message-ID: <20190801144707.vprfi4yy2shxmtyw@pengutronix.de>
Date:   Thu, 1 Aug 2019 16:47:07 +0200
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Schrempf Frieder <frieder.schrempf@...tron.de>
Cc:     "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "linux-imx@....com" <linux-imx@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Jiri Slaby <jslaby@...e.com>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] serial: mctrl_gpio: Avoid probe failures in case of
 missing gpiolib

On Thu, Aug 01, 2019 at 12:46:42PM +0000, Schrempf Frieder wrote:
> From: Frieder Schrempf <frieder.schrempf@...tron.de>
> 
> If CONFIG_GPIOLIB is not enabled, mctrl_gpio_init() and
> mctrl_gpio_init_noauto() will currently return an error pointer with
> -ENOSYS. As the mctrl GPIOs are usually optional, drivers need to
> check for this condition to allow continue probing.
> 
> To avoid the need for this check in each driver, we return NULL
> instead, as all the mctrl_gpio_*() functions are skipped anyway.
> We also adapt mctrl_gpio_to_gpiod() to be in line with this change.
> 
> Signed-off-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> ---
>  drivers/tty/serial/serial_mctrl_gpio.c | 3 +++
>  drivers/tty/serial/serial_mctrl_gpio.h | 6 +++---
>  drivers/tty/serial/sh-sci.c            | 2 +-

I'd split the sh-sci change in a separate patch. And there is another
instance in drivers/tty/serial/8250/8250_core.c that should be dropped.

Other than that looks good.

Best regards
Uwe

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