[PATCH v2] pinctrl: mediatek: paris: bypass pinctrl GPIO layer in set GPIO direction

[Linus Walleij]

On Tue, May 5, 2026 at 12:40 PM Chen-Yu Tsai <wenst at chromium.org> wrote:

> pinctrl_gpio_direction_input() / pinctrl_gpio_direction_output() take
> the pinctrl mutex. This causes a gpiochip operations to need to sleep.
> Worse yet, the .can_sleep field in the gpiochip is not set. This causes
> the shared GPIO proxy to trip over, as it uses gpiod_cansleep() to check
> whether it can use a spinlock or needs a mutex. In this case, it ends
> up taking a spinlock, then calls pinctrl_gpio_direction_output(), which
> takes a mutex. This causes a huge warning.
>
> While this class of Mediatek hardware does not have separate clear/set
> registers, the pinctrl context has a spinlock that is taken whenever
> a register read-modify-write is done. Also, once the GPIO function is
> selected / muxed in, further GPIO operations do not involve pinctrl
> operations or state. The GPIO direction and level values do not require
> toggling the pinmux or any other pin config options.
>
> Switch to directly calling mtk_pinmux_gpio_set_direction() in the GPIO
> set direction callbacks to avoid taking the pinctrl mutex. Drop the
> .gpio_set_direction field in mtk_pmxops to signal we are no longer using
> the pinctrl GPIO layer for setting the direction.
>
> Signed-off-by: Chen-Yu Tsai <wenst at chromium.org>

Patch applied, thanks for your perseverance Chen-Yu!

Yours,
Linus Walleij