When a GPIO RIF configuration is in semaphore mode, and the semaphore
hasn't been taken before configuring the GPIO, the write operations
silently fail.

To avoid a silent fail when applying a pinctrl, if the pins that are
being configured are in semaphore mode, take the semaphore. Note that
there is no proper release of the RIF semaphore yet for pinctrl.

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
---
 drivers/pinctrl/stm32/pinctrl-stm32.c | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/drivers/pinctrl/stm32/pinctrl-stm32.c b/drivers/pinctrl/stm32/pinctrl-stm32.c
index ceb9e19f2290..6a99708a5a23 100644
--- a/drivers/pinctrl/stm32/pinctrl-stm32.c
+++ b/drivers/pinctrl/stm32/pinctrl-stm32.c
@@ -362,11 +362,9 @@ static int stm32_gpio_request(struct gpio_chip *chip, unsigned offset)
 		return -EINVAL;
 	}
 
-	if (bank->rif_control) {
-		if (!stm32_gpio_rif_acquire_semaphore(bank, offset)) {
-			dev_err(pctl->dev, "pin %d not available.\n", pin);
-			return -EINVAL;
-		}
+	if (bank->rif_control && !stm32_gpio_rif_acquire_semaphore(bank, offset)) {
+		dev_err(pctl->dev, "pin %d not available.\n", offset);
+		return -EACCES;
 	}
 
 	return pinctrl_gpio_request(chip, offset);
@@ -1040,7 +1038,9 @@ static int stm32_pmx_gpio_set_direction(struct pinctrl_dev *pctldev,
 static int stm32_pmx_request(struct pinctrl_dev *pctldev, unsigned int gpio)
 {
 	struct stm32_pinctrl *pctl = pinctrl_dev_get_drvdata(pctldev);
+	unsigned int offset = stm32_gpio_pin(gpio);
 	struct pinctrl_gpio_range *range;
+	struct stm32_gpio_bank *bank;
 
 	range = pinctrl_find_gpio_range_from_pin_nolock(pctldev, gpio);
 	if (!range) {
@@ -1048,11 +1048,20 @@ static int stm32_pmx_request(struct pinctrl_dev *pctldev, unsigned int gpio)
 		return -EINVAL;
 	}
 
-	if (!gpiochip_line_is_valid(range->gc, stm32_gpio_pin(gpio))) {
+	if (!gpiochip_line_is_valid(range->gc, offset)) {
 		dev_warn(pctl->dev, "Can't access gpio %d\n", gpio);
 		return -EACCES;
 	}
 
+	bank = gpiochip_get_data(range->gc);
+	if (!bank)
+		return -ENODEV;
+
+	if (bank->rif_control && !stm32_gpio_rif_acquire_semaphore(bank, offset)) {
+		dev_err(pctl->dev, "pin %d not available.\n", offset);
+		return -EACCES;
+	}
+
 	return 0;
 }
 
@@ -1394,6 +1403,11 @@ static int stm32_pconf_parse_conf(struct pinctrl_dev *pctldev,
 		return -EACCES;
 	}
 
+	if (bank->rif_control && !stm32_gpio_rif_acquire_semaphore(bank, offset)) {
+		dev_err(pctl->dev, "pin %d not available.\n", offset);
+		return -EACCES;
+	}
+
 	switch (param) {
 	case PIN_CONFIG_DRIVE_PUSH_PULL:
 		ret = stm32_pconf_set_driving(bank, offset, 0);
@@ -2014,16 +2028,21 @@ static int __maybe_unused stm32_pinctrl_restore_gpio_regs(
 	if (!range)
 		return 0;
 
+	bank = gpiochip_get_data(range->gc);
+
 	if (!gpiochip_line_is_valid(range->gc, offset))
 		return 0;
 
+	if (bank->rif_control && !stm32_gpio_rif_acquire_semaphore(bank, offset)) {
+		dev_err(pctl->dev, "pin %d not available.\n", offset);
+		return -EACCES;
+	}
+
 	pin_is_irq = gpiochip_line_is_irq(range->gc, offset);
 
 	if (!desc || (!pin_is_irq && !desc->gpio_owner))
 		return 0;
 
-	bank = gpiochip_get_data(range->gc);
-
 	mode = bank->pin_backup[offset].mode;
 	ret = stm32_pmx_set_mode(bank, offset, mode, bank->pin_backup[offset].alt);
 	if (ret)

---
base-commit: 2aea4b47e7a5ef171645302b036fa5fb21837274
change-id: 20251104-gpio_semaphore-7ab42f316c5d

Best regards,
-- 
Gatien Chevallier <gatien.chevallier@foss.st.com>

On Wed, Nov 5, 2025 at 11:50 AM Gatien Chevallier
<gatien.chevallier@foss.st.com> wrote:

> When a GPIO RIF configuration is in semaphore mode, and the semaphore
> hasn't been taken before configuring the GPIO, the write operations
> silently fail.
>
> To avoid a silent fail when applying a pinctrl, if the pins that are
> being configured are in semaphore mode, take the semaphore. Note that
> there is no proper release of the RIF semaphore yet for pinctrl.
>
> Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>

Patch applied.

Yours,
Linus Walleij