[PATCH] pinctrl: mediatek: common-v1: Directly modify registers to set GPIO direction

[Linus Walleij]

On Mon, Apr 27, 2026 at 8:17 AM 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.
>
> Since the Mediatek hardware has separate clear/set registers, there is
> no risk of clobbering other bits like with a read-modify-write pattern.
> Switch to directly setting the GPIO direction register bits to avoid
> the mutex.
>
> Signed-off-by: Chen-Yu Tsai <wenst at chromium.org>

Here you need to at least delete the assignment of mtk_pmx_gpio_set_direction()
from:

static const struct pinmux_ops mtk_pmx_ops = {
        .get_functions_count    = mtk_pmx_get_funcs_cnt,
        .get_function_name      = mtk_pmx_get_func_name,
        .get_function_groups    = mtk_pmx_get_func_groups,
        .set_mux                = mtk_pmx_set_mux,
        .gpio_set_direction     = mtk_pmx_gpio_set_direction,

^ Here, it should no longer be used, right?

Yours,
Linus Walleij