[PATCH v2] gpio: convince line to become input in irq helper

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

The generic IRQ helper library just checks if the IRQ line is
set as input before activating it for interrupts. As we
recently started to check things better with .get_dir() it
turns out that it's good to try to convince the line to become
an input before attempting to lock it as IRQ.

Cc: Björn Andersson <bjorn.andersson@xxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
ChangeLog v1->v2:
- Propagate the error from .direction_input() so we can rely on
  it being used.
---
 drivers/gpio/gpiolib.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 5a21a6acf8af..b195ec406ff4 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1505,6 +1505,25 @@ static int gpiochip_irq_reqres(struct irq_data *d)
 	if (!try_module_get(chip->gpiodev->owner))
 		return -ENODEV;
 
+	/*
+	 * If it is possible to switch this GPIO to an input
+	 * this is a good time to do it.
+	 */
+	if (chip->direction_input) {
+		struct gpio_desc *desc;
+		int ret;
+
+		desc = gpiochip_get_desc(chip, d->hwirq);
+		if (IS_ERR(desc))
+			return PTR_ERR(desc);
+
+	        ret = chip->direction_input(chip, d->hwirq);
+		if (ret)
+			return ret;
+
+		clear_bit(FLAG_IS_OUT, &desc->flags);
+	}
+
 	if (gpiochip_lock_as_irq(chip, d->hwirq)) {
 		chip_err(chip,
 			"unable to lock HW IRQ %lu for IRQ\n",
-- 
2.4.11

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