linux-kernel - Re: [PATCH 4/4] tty/serial: sh-sci: remove uneeded IS_ERR_OR

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Message-ID: <20170306085842.yijkfpqi3adcedmm@pengutronix.de>
Date:   Mon, 6 Mar 2017 09:58:42 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Richard Genoud <richard.genoud@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Janusz Uzycki <j.uzycki@...roma.com.pl>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 4/4] tty/serial: sh-sci: remove uneeded IS_ERR_OR_NULL
 calls

Hello Geert,

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.

Best regards
Uwe

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