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

[Linus Walleij <linus.walleij@linaro.org>]

On Tue, Dec 2, 2014 at 2:42 PM, Alexandre Courbot <acourbot@nvidia.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@linux-m68k.org>
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>

Patch applied with Geert's tested tag.

Yours,
Linus Walleij