Re: [PATCH 1/2] gpiolib: Add for_each_gpio_suffix() helper

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Stefan Roese <sr@denx.de>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Pavel Machek <pavel@denx.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH 1/2] gpiolib: Add for_each_gpio_suffix() helper
Date: Wed, 14 Aug 2019 15:32:33 +0200	[thread overview]
Message-ID: <CAMuHMdX7wa+0OL8eOqFhELJNHKGRp_aWrZvEVAw9-ci-_6tMVw@mail.gmail.com> (raw)
In-Reply-To: <2f78c3f4-08a4-480e-ff70-8526d0a671ba@denx.de>

Hi Stefan,

On Wed, Aug 14, 2019 at 3:17 PM Stefan Roese <sr@denx.de> wrote:
> On 14.08.19 10:48, Linus Walleij wrote:
> > On Mon, Aug 12, 2019 at 1:18 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> >> On Sat, Aug 10, 2019 at 10:27 AM Linus Walleij <linus.walleij@linaro.org> wrote:
> >>> On Thu, Aug 8, 2019 at 3:25 PM Stefan Roese <sr@denx.de> wrote:
> >>>> Add a helper macro to enable the interation over all supported GPIO
> >>>> suffixes (currently "gpios" & "gpio"). This will be used by the serial
> >>>> mctrl code to check, if a GPIO property exists before requesting it.
> >>>>
> >>>> Signed-off-by: Stefan Roese <sr@denx.de>
> >>>> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> >>>> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> >>>> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> >>>> Cc: Pavel Machek <pavel@denx.de>
> >>>> Cc: Linus Walleij <linus.walleij@linaro.org>
> >>>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >>>
> >>> I really like this patch, it makes things so much more readable.
> >>
> >> Do we really need to spread this *-gpio" legacy support all over the kernel?
> >
> > Not really :/
> >
> > Isn't it possible to use something like gpiod_count(dev, "foo") to
> > check for any GPIOs instead?
>
> Good idea. I can rework my patch to use gpiod_count() to check if the
> GPIO exists before requesting it. This way, we're not spreading the
> legacy "-gpio" support any more.
>
> But I'm unsure, if I should change the string malloc (kasprintf) to the
> fixed length string on the stack as I've done in this patch version.

Would that work for the mctrl-gpio case?
The issue is that there exist GPIOs (found by index), but they don't match
the passed con_id.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds