[PATCH v2 0/2] gpio: i.MX: make _get_value() able to read output pin state

[PATCH v2 0/2] gpio: i.MX: make _get_value() able to read output pin state

[Maud Spierings via B4 Relay]

Make _get_value() read back the dr register instead of the psr register
when the direction is set to output. Now _get_value() can actually read
the state of an output gpio instead of being always low.

Also add a note in the migration guide file.

Signed-off-by: Maud Spierings <maud_spierings@hotmail.com>
---
Changes in v2:
- Move the extra commit comment into the commit [1/2]
- Actually add a note to the migration file [2/2]
- Link to v1: https://lore.kernel.org/r/20251015-imx_gpio-v1-0-e57925f906bb@hotmail.com

---
Maud Spierings (2):
      gpio: i.MX: make _get_value() able to read output pin state
      Documentation: migration-2025.11.0: add note about new gpio behaviour

 .../migration-guides/migration-2025.11.0.rst          |  7 +++++++
 drivers/gpio/gpio-imx.c                               | 19 +++++++++++--------
 2 files changed, 18 insertions(+), 8 deletions(-)
---
base-commit: 8defba1d0ab1aef9dd5d57710e18d0d02e2c48e2
change-id: 20251015-imx_gpio-46efe1e7abd3

Best regards,
-- 
Maud Spierings <maud_spierings@hotmail.com>

[PATCH v2 1/2] gpio: i.MX: make _get_value() able to read output pin state

[Maud Spierings via B4 Relay]

From: Maud Spierings <maud_spierings@hotmail.com>

Make _get_value() read back the dr register instead of the psr register
when the direction is set to output. Now _get_value() can actually read
the state of an output gpio instead of being always low.

This aproach is also used by u-boot and Linux.

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Maud Spierings <maud_spierings@hotmail.com>
---
 drivers/gpio/gpio-imx.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/gpio/gpio-imx.c b/drivers/gpio/gpio-imx.c
index d9499c66cd..bb14c56399 100644
--- a/drivers/gpio/gpio-imx.c
+++ b/drivers/gpio/gpio-imx.c
@@ -89,24 +89,27 @@ static int imx_gpio_direction_output(struct gpio_chip *chip, unsigned gpio, int
 	return 0;
 }
 
-static int imx_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
+static int imx_get_direction(struct gpio_chip *chip, unsigned offset)
 {
 	struct imx_gpio_chip *imxgpio = container_of(chip, struct imx_gpio_chip, chip);
 	void __iomem *base = imxgpio->base;
-	u32 val;
-
-	val = readl(base + imxgpio->regs->psr);
+	u32 val = readl(base + imxgpio->regs->gdir);
 
-	return val & (1 << gpio) ? 1 : 0;
+	return (val & (1 << offset)) ? GPIOF_DIR_OUT : GPIOF_DIR_IN;
 }
 
-static int imx_get_direction(struct gpio_chip *chip, unsigned offset)
+static int imx_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
 {
 	struct imx_gpio_chip *imxgpio = container_of(chip, struct imx_gpio_chip, chip);
 	void __iomem *base = imxgpio->base;
-	u32 val = readl(base + imxgpio->regs->gdir);
+	u32 val;
 
-	return (val & (1 << offset)) ? GPIOF_DIR_OUT : GPIOF_DIR_IN;
+	if (imx_get_direction(chip, gpio) == GPIOF_DIR_IN)
+		val = readl(base + imxgpio->regs->psr);
+	else
+		val = readl(base + imxgpio->regs->dr);
+
+	return val & (1 << gpio) ? 1 : 0;
 }
 
 static struct gpio_ops imx_gpio_ops = {

-- 
2.51.1.dirty

[PATCH v2 2/2] Documentation: migration-2025.11.0: add note about new gpio behaviour

[Maud Spierings via B4 Relay]

From: Maud Spierings <maud_spierings@hotmail.com>

The previous change, changes the behaviour of reading gpio values, make
a note of it in the migration guide.

Signed-off-by: Maud Spierings <maud_spierings@hotmail.com>
---
 Documentation/migration-guides/migration-2025.11.0.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/migration-guides/migration-2025.11.0.rst b/Documentation/migration-guides/migration-2025.11.0.rst
new file mode 100644
index 0000000000..9cbc46acc3
--- /dev/null
+++ b/Documentation/migration-guides/migration-2025.11.0.rst
@@ -0,0 +1,7 @@
+i.MX GPIOs
+----------
+
+Reading output GPIOs now returns the configured output level instead
+of reading back the input register. This aligns us with what Linux
+is doing, but may falsify readings of single-ended GPIOs that have
+the SION bit configured.

-- 
2.51.1.dirty

Re: [PATCH v2 0/2] gpio: i.MX: make _get_value() able to read output pin state

[Sascha Hauer]

On Sat, 18 Oct 2025 11:59:46 +0200, Maud Spierings via B4 Relay wrote:
> Make _get_value() read back the dr register instead of the psr register
> when the direction is set to output. Now _get_value() can actually read
> the state of an output gpio instead of being always low.
> 
> Also add a note in the migration guide file.
> 
> 
> [...]

Applied, thanks!

[1/2] gpio: i.MX: make _get_value() able to read output pin state
      https://git.pengutronix.de/cgit/barebox/commit/?id=9749d5bb4cfd (link may not be stable)
[2/2] Documentation: migration-2025.11.0: add note about new gpio behaviour
      https://git.pengutronix.de/cgit/barebox/commit/?id=5e531faed8b2 (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>