[alsa-devel] [PATCH] ASoC: simple-card: Add mic and hp detect gpios.

[Mark Brown]

On Tue, Oct 07, 2014 at 03:10:01PM +0200, Geert Uytterhoeven wrote:
> On Tue, Oct 7, 2014 at 2:38 PM, Mark Brown <broonie at kernel.org> wrote:

> > The fix here is to not allow 0 as a GPIO in the core code (which
> > should've been there already).

> Unfortunately it's not there.

> And it's not as simple as changing the definition of gpio_is_valid()
> (crash in gpio_get_value()):

>     gpiochip_add: GPIOs 0..211 (r8a7740_pfc) failed to register
>     sh-pfc pfc-r8a7740: failed to init GPIO chip, ignoring...
>     sh-pfc pfc-r8a7740: r8a7740_pfc support registered
>     Unable to handle kernel NULL pointer dereference at virtual address 0000004c

Right, obviously it's not going to work if the platform actually uses 0
as a valid GPIO.

> Quoting Linus (https://lkml.org/lkml/2014/9/4/464):
> "Fixing the old global GPIO numberspace API is a waste of time IMO".

> Hence I've just sent a patch to initialize the GPIO numbers with -ENOENT.

I do think it's worth renumbering the platforms since it's *relatively*
little work per platform compared to completing the gpiod transition.
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