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@chromium.org>
---
This was

    pinctrl: mediatek: paris: Directly modify registers to set GPIO direction

Changes since v1:
- Dropped .gpio_set_direction field in mtk_pmxops
- Call mtk_pinmux_gpio_set_direction() from
  mtk_gpio_direction_(output|input)()
- Updated commit subject and message
- Link to v1:
  https://lore.kernel.org/all/20260427021021.2049015-1-wenst@chromium.org/
---
 drivers/pinctrl/mediatek/pinctrl-paris.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/pinctrl/mediatek/pinctrl-paris.c b/drivers/pinctrl/mediatek/pinctrl-paris.c
index 6bf37d8085fa..23f04b24fd65 100644
--- a/drivers/pinctrl/mediatek/pinctrl-paris.c
+++ b/drivers/pinctrl/mediatek/pinctrl-paris.c
@@ -771,7 +771,6 @@ static const struct pinmux_ops mtk_pmxops = {
 	.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_pinmux_gpio_set_direction,
 	.gpio_request_enable	= mtk_pinmux_gpio_request_enable,
 };
 
@@ -886,19 +885,22 @@ static int mtk_gpio_set(struct gpio_chip *chip, unsigned int gpio, int value)
 
 static int mtk_gpio_direction_input(struct gpio_chip *chip, unsigned int gpio)
 {
-	return pinctrl_gpio_direction_input(chip, gpio);
+	struct mtk_pinctrl *hw = gpiochip_get_data(chip);
+
+	return mtk_pinmux_gpio_set_direction(hw->pctrl, NULL, gpio, true);
 }
 
 static int mtk_gpio_direction_output(struct gpio_chip *chip, unsigned int gpio,
 				     int value)
 {
+	struct mtk_pinctrl *hw = gpiochip_get_data(chip);
 	int ret;
 
 	ret = mtk_gpio_set(chip, gpio, value);
 	if (ret)
 		return ret;
 
-	return pinctrl_gpio_direction_output(chip, gpio);
+	return mtk_pinmux_gpio_set_direction(hw->pctrl, NULL, gpio, false);
 }
 
 static int mtk_gpio_to_irq(struct gpio_chip *chip, unsigned int offset)
-- 
2.54.0.545.g6539524ca2-goog

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

Patch applied, thanks for your perseverance Chen-Yu!

Yours,
Linus Walleij