gpiolib: skip unwanted events, don't convert them to opposite edge

The previous fix for filtering out of unwatched events was not entirely
correct. Instead of skipping the events we don't want, they are now
interpreted as events with opposing edge.

In order to fix it: always read the GPIO line value on interrupt and
only emit the event if it corresponds with the event type we requested.

Cc: stable@vger.kernel.org
Fixes: ad537b822577 ("gpiolib: fix filtering out unwanted events")
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 9568708a550b..cd003b74512f 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -704,24 +704,23 @@ static irqreturn_t lineevent_irq_thread(int irq, void *p)
 {
         struct lineevent_state *le = p;
         struct gpioevent_data ge;
-        int ret;
+        int ret, level;
 
         ge.timestamp = ktime_get_real_ns();
+        level = gpiod_get_value_cansleep(le->desc);
 
         if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE
             && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
-                int level = gpiod_get_value_cansleep(le->desc);
-
                 if (level)
                         /* Emit low-to-high event */
                         ge.id = GPIOEVENT_EVENT_RISING_EDGE;
                 else
                         /* Emit high-to-low event */
                         ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
-        } else if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE) {
+        } else if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE && level) {
                 /* Emit low-to-high event */
                 ge.id = GPIOEVENT_EVENT_RISING_EDGE;
-        } else if (le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
+        } else if (le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE && !level) {
                 /* Emit high-to-low event */
                 ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
         } else {