[PATCH] gpio: fix locking open drain IRQ lines

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

We provided the right semantics on open drain lines being
by definition output but incidentally the irq set up function
would only allow IRQs on lines that were "not output".

Fix the semantics to allow output open drain lines to be used
for IRQs.

Reported-by: Hans Verkuil <hverkuil@xxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 256efaea1fdc ("gpiolib: fix up emulated open drain outputs")
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
 drivers/gpio/gpiolib.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index b4b5792fe2ff..edd74ff31cea 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4220,7 +4220,9 @@ int gpiochip_lock_as_irq(struct gpio_chip *gc, unsigned int offset)
 		}
 	}
 
-	if (test_bit(FLAG_IS_OUT, &desc->flags)) {
+	/* To be valid for IRQ the line needs to be input or open drain */
+	if (test_bit(FLAG_IS_OUT, &desc->flags) &&
+	    !test_bit(FLAG_OPEN_DRAIN, &desc->flags)) {
 		chip_err(gc,
 			 "%s: tried to flag a GPIO set as output for IRQ\n",
 			 __func__);
-- 
2.25.4