--- /dev/null
+From 79bb71bd1d93197ce227fa167b450b633f30a52b Mon Sep 17 00:00:00 2001
+From: Linus Walleij <linus.walleij@linaro.org>
+Date: Wed, 15 Jun 2016 22:57:38 +0200
+Subject: gpio: make sure gpiod_to_irq() returns negative on NULL desc
+
+From: Linus Walleij <linus.walleij@linaro.org>
+
+commit 79bb71bd1d93197ce227fa167b450b633f30a52b upstream.
+
+commit 54d77198fdfbc4f0fe11b4252c1d9c97d51a3264
+("gpio: bail out silently on NULL descriptors")
+doesn't work for gpiod_to_irq(): drivers assume that NULL
+descriptors will give negative IRQ numbers in return.
+
+It has been pointed out that returning 0 is NO_IRQ and that
+drivers should be amended to treat this as an error, but that
+is for the longer term: now let us repair the semantics.
+
+Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
+Reported-by: Hans de Goede <hdegoede@redhat.com>
+Tested-by: Hans de Goede <hdegoede@redhat.com>
+Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/gpio/gpiolib.c | 9 ++++++++-
+ 1 file changed, 8 insertions(+), 1 deletion(-)
+
+--- a/drivers/gpio/gpiolib.c
++++ b/drivers/gpio/gpiolib.c
+@@ -2006,7 +2006,14 @@ int gpiod_to_irq(const struct gpio_desc
+ struct gpio_chip *chip;
+ int offset;
+
+- VALIDATE_DESC(desc);
++ /*
++ * Cannot VALIDATE_DESC() here as gpiod_to_irq() consumer semantics
++ * requires this function to not return zero on an invalid descriptor
++ * but rather a negative error number.
++ */
++ if (!desc || !desc->gdev || !desc->gdev->chip)
++ return -EINVAL;
++
+ chip = desc->gdev->chip;
+ offset = gpio_chip_hwgpio(desc);
+ return chip->to_irq ? chip->to_irq(chip, offset) : -ENXIO;