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

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

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.

Thanks for your thorough investigation of the issue!

Yours,
Linus Walleij