linux-kernel - Re: [PATCH v2] gpio: fix deferred probe detection for legacy API

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Date:	Tue, 2 Dec 2014 15:30:02 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Alexandre Courbot <acourbot@...dia.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Alexandre Courbot <gnurou@...il.com>
Subject: Re: [PATCH v2] gpio: fix deferred probe detection for legacy API

Hi Alexander,

On Tue, Dec 2, 2014 at 3:15 PM, Alexandre Courbot <acourbot@...dia.com> wrote:
> Commit 14e85c0e69d5 ("gpio: remove gpio_descs global array") changed
> gpio_to_desc()'s behavior to return NULL not only for GPIOs numbers
> not in the valid range, but also for all GPIOs whose controller has not
> been probed yet. Although this behavior is more correct (nothing hints
> that these GPIO numbers will be populated later), this affects
> gpio_request() and gpio_request_one() which call gpiod_request() with a
> NULL descriptor, causing it to return -EINVAL instead of the expected
> -EPROBE_DEFER for a non-probed GPIO.
>
> gpiod_request() is only called with a descriptor obtained from
> gpio_to_desc() from these two functions, so address the issue there.
>
> Other ways to obtain GPIOs rely on well-defined mappings and can thus
> return -EPROBE_DEFER only for relevant GPIOs, and are thus not affected
> by this issue.
>
> Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
> ---
> v2:
> - Add Geert's Tested-by
> - Only display scary warning on gpio_to_desc() is the GPIO is outside
>   the valid range (pre gpio_desc array removal behavior)

Thanks, the scary warnings are gone, together with a few superfluous
"gpio-0 (?): gpiod_request: status -517" messages.

Have a good night!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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
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