HID: i2c-hid: force the IRQ level trigger only when not set

Instead of forcing the level trigger of the IRQ, we can count
on ACPI or OF to set it up for us.

The first release of the HID over I2C specification mentioned
that the level trigger needed to be active low. In the latest
version of the specification, there is no such explicit mention,
so it's better to not assume one.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/i2c-hid/i2c-hid.c

@@ -22,6 +22,7 @@
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/input.h>
+#include <linux/irq.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/pm.h>
@@ -858,13 +859,16 @@ static struct hid_ll_driver i2c_hid_ll_driver = {
 static int i2c_hid_init_irq(struct i2c_client *client)
 {
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
+	unsigned long irqflags = 0;
 	int ret;
 
 	dev_dbg(&client->dev, "Requesting IRQ: %d\n", client->irq);
 
+	if (!irq_get_trigger_type(client->irq))
+		irqflags = IRQF_TRIGGER_LOW;
+
 	ret = request_threaded_irq(client->irq, NULL, i2c_hid_irq,
-			IRQF_TRIGGER_LOW | IRQF_ONESHOT,
-			client->name, ihid);
+				   irqflags | IRQF_ONESHOT, client->name, ihid);
 	if (ret < 0) {
 		dev_warn(&client->dev,
 			"Could not register for %s interrupt, irq = %d,"