[PATCH v2] pinctrl: mediatek: common-v1: bypass pinctrl GPIO layer in set GPIO direction

[Chen-Yu Tsai]

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.
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_pmx_gpio_set_direction() in the GPIO set
direction callbacks to avoid taking the pinctrl mutex. Drop the
.gpio_set_direction field in mtk_pmx_ops 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>
---
Only compile tested. Accidentally fixed the wrong file when my target
actually used pinctrl-paris.c

This was

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

Changes since v1:
- Dropped .gpio_set_direction field in mtk_pmx_ops
- Fixed direction in mtk_gpio_direction_output()
- Updated commit subject and message
- Link to v1:
  https://lore.kernel.org/all/20260427061720.2393355-1-wenst@chromium.org/
---
 drivers/pinctrl/mediatek/pinctrl-mtk-common.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/pinctrl/mediatek/pinctrl-mtk-common.c b/drivers/pinctrl/mediatek/pinctrl-mtk-common.c
index 3f518dce6d23..dd2c8aa03938 100644
--- a/drivers/pinctrl/mediatek/pinctrl-mtk-common.c
+++ b/drivers/pinctrl/mediatek/pinctrl-mtk-common.c
@@ -802,20 +802,27 @@ static const struct pinmux_ops mtk_pmx_ops = {
 	.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,
 	.gpio_request_enable	= mtk_pmx_gpio_request_enable,
 };
 
+static int mtk_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	struct mtk_pinctrl *pctl = gpiochip_get_data(chip);
+
+	return mtk_pmx_gpio_set_direction(pctl->pctl_dev, NULL, offset, true);
+}
+
 static int mtk_gpio_direction_output(struct gpio_chip *chip,
 					unsigned offset, int value)
 {
+	struct mtk_pinctrl *pctl = gpiochip_get_data(chip);
 	int ret;
 
 	ret = mtk_gpio_set(chip, offset, value);
 	if (ret)
 		return ret;
 
-	return pinctrl_gpio_direction_output(chip, offset);
+	return mtk_pmx_gpio_set_direction(pctl->pctl_dev, NULL, offset, false);
 }
 
 static int mtk_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
@@ -895,7 +902,7 @@ static const struct gpio_chip mtk_gpio_chip = {
 	.request		= gpiochip_generic_request,
 	.free			= gpiochip_generic_free,
 	.get_direction		= mtk_gpio_get_direction,
-	.direction_input	= pinctrl_gpio_direction_input,
+	.direction_input	= mtk_gpio_direction_input,
 	.direction_output	= mtk_gpio_direction_output,
 	.get			= mtk_gpio_get,
 	.set			= mtk_gpio_set,
-- 
2.54.0.545.g6539524ca2-goog