On Tue, Oct 07, 2014 at 03:10:01PM +0200, Geert Uytterhoeven wrote:

On Tue, Oct 7, 2014 at 2:38 PM, Mark Brown [off-list ref] wrote:

quoted

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.