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

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Message-ID: <CAAVeFuJrLth2bT20i0MoPYhLFidNbUEfoUjqdb0oNg6ARCZryg@mail.gmail.com>
Date:	Tue, 2 Dec 2014 23:20:27 +0900
From:	Alexandre Courbot <gnurou@...il.com>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Alexandre Courbot <acourbot@...dia.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] gpio: fix deferred probe detection for legacy API

On Tue, Dec 2, 2014 at 11:19 PM, Linus Walleij <linus.walleij@...aro.org> wrote:
> On Tue, Dec 2, 2014 at 2:42 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>
>
> Patch applied with Geert's tested tag.

I just send a v2 which only prints the warning if the GPIO is outside
of the valid range (better for legacy API).
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