Re: [PATCH] gpio: rcar: select General Output Register to set output states

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Linus,

On Sun, Dec 16, 2018 at 1:19 AM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> On Mon, Dec 10, 2018 at 3:22 PM Vladimir Zapolskiy
> <vladimir_zapolskiy@xxxxxxxxxx> wrote:
> > R-Car GPIO controller provides two interfaces to set GPIO line output
> > signal state, and for a particular GPIO line the selected interface is
> > determined by OUTDTSEL bit value.
> >
> > At the moment the driver supports only one of two interfaces, namely
> > OUTDT General Output Register is used to control the output signal.
> >
> > While this selection is the default one on reset, it is not explicitly
> > configured on probe, thus it might be possible that kernel and userspace
> > consumers of a GPIO won't be able to set the wanted GPIO output signal.
> >
> > Below is a simple test case to reproduce the described problem and
> > verify this fix in the kernel on H3 ULCB by setting non-default OUTDTSEL
> > configuration from a bootloader:
> >
> >   u-boot    > mw.l 0xe6055440 0x3000 1
> >   ...
> >   userspace > echo -n default-on > /sys/devices/platform/leds/leds/led5/trigger
> >   userspace > echo -n default-on > /sys/devices/platform/leds/leds/led6/trigger
> >
> > Fixes: 119f5e448d32c ("gpio: Renesas R-Car GPIO driver V3")
> > Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx>
>
> Patch applied for devel as "non-urgent fix" as I can't see any
> immediate regressions.

Unfortunately the driver now writes unconditionally to a register that does
not exist on R-Car Gen1. Hence please revert the patch.

Thanks!

Gr{oetje,eeting}s,

                        Geert

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

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