(re-added some context, CC Linus, Alexandre, linux-gpio)

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

On Tue, Oct 07, 2014 at 02:32:57PM +0200, Geert Uytterhoeven wrote:

quoted

Unfortunately there's no equivalent code for platform data, and the
uninitialized default of 0 for gpio_hp_det and gpio_mic_det doesn't
play well with asm-generic's gpio_is_valid():

static inline bool gpio_is_valid(int number)
{
        return number >= 0 && number < ARCH_NR_GPIOS;
}

Hence on r8a7740/armadillo-legacy, which uses platform devices instead of DT:

quoted

    sh-mobile-hdmi sh-mobile-hdmi: SH Mobile HDMI Audio Codec
    sh-mobile-hdmi sh-mobile-hdmi: ASoC: DAPM unknown pin Headphones
    sh-mobile-hdmi sh-mobile-hdmi: ASoC: DAPM unknown pin Mic Jack

quoted

After that the kernel log is spammed ca. 7 times per second with:

quoted

    sh-mobile-hdmi sh-mobile-hdmi: ASoC: DAPM unknown pin Headphones

quoted

Reverting commit 3fe240326cc395c66 ("ASoC: simple-card: Add mic and
hp detect gpios.") fixes this.

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

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.

Gr{oetje,eeting}s,

                        Geert

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