[PATCH v4 2/2] i2c: core: support recovery for single-ended GPIOs

[Jie Li]

Currently, i2c_init_recovery() only assigns the set_sda/set_scl
hooks if gpiod_get_direction() returns GPIO_LINE_DIRECTION_OUT.

This logic fails on certain SoC controllers where open-drain lines
in a high-impedance state are physically reported as inputs. This
leads to a "deadlock" where the I2C core refuses to assign the
recovery hooks because it incorrectly assumes the pins are
input-only, even though they are fully capable of driving the bus
low for recovery.

Update the recovery initialization to use the new
gpiod_is_single_ended() helper. If a GPIO is configured as
open-drain or open-source in the firmware, it is safe to assume
it can be used for bus recovery, even if the current hardware
direction is reported as input.

Signed-off-by: Jie Li <jie.i.li@xxxxxxxxx>
Reviewed-by: Linus Walleij <linusw@xxxxxxxxxx>
Acked-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---
 drivers/i2c/i2c-core-base.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 9c46147e3506..a3c33e804d47 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -445,8 +445,8 @@ static int i2c_init_recovery(struct i2c_adapter *adap)
 		bri->set_scl = set_scl_gpio_value;
 		if (bri->sda_gpiod) {
 			bri->get_sda = get_sda_gpio_value;
-			/* FIXME: add proper flag instead of '0' once available */
-			if (gpiod_get_direction(bri->sda_gpiod) == 0)
+			if (gpiod_get_direction(bri->sda_gpiod) == GPIO_LINE_DIRECTION_OUT ||
+			    gpiod_is_single_ended(bri->sda_gpiod))
 				bri->set_sda = set_sda_gpio_value;
 		}
 	} else if (bri->recover_bus == i2c_generic_scl_recovery) {
-- 
2.43.0