linux-kernel - Re: [PATCH 1/2 v9] serial: mctrl_gpio: Check if GPIO property exisits before requesting it

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Message-ID: <20190625111948.GV9224@smile.fi.intel.com>
Date:   Tue, 25 Jun 2019 14:19:48 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Stefan Roese <sr@...x.de>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Yegor Yefremov <yegorslists@...glemail.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Giulio Benetti <giulio.benetti@...ronovasrl.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 1/2 v9] serial: mctrl_gpio: Check if GPIO property
 exisits before requesting it

On Tue, Jun 25, 2019 at 07:27:33AM +0200, Stefan Roese wrote:
> On 24.06.19 17:35, Geert Uytterhoeven wrote:
> > On Mon, Jun 24, 2019 at 5:29 PM Stefan Roese <sr@...x.de> wrote:
> > > On 24.06.19 10:42, Geert Uytterhoeven wrote:

> > > Should both options be supported ("cts-gpio" vs "cts-gpios")?
> > > Documentation/devicetree/bindings/serial/serial.txt only mentions
> > > the "-gpios" variant.
> > 
> > Well, the "-gpio" variant is deprecated, but still supported by
> > devm_gpiod_get_index_optional(), and there are active users in upstream
> > DTS files.
> > 
> > My main objection is (trying to) replicate the matching logic inside
> > gpiolib.c, causing subtle semantic differences. And keeping it consistent,
> > of course.
> > 
> > It would be nice if this could be fixed inside acpi_find_gpio(), so
> > users don't need to be updated.  There may be other subsystems where
> > the difference between DT and ACPI may cause issues, unbeknownst.
> 
> Sure, I can fix this. I would prefer to do this in a follow-up patch
> though, if nobody objects.

In case if you are going to do this, use approach from GPIO library. Perhaps,
it may require to create something like for_each_gpio_suffix() helper.

-- 
With Best Regards,
Andy Shevchenko