3.10.71 -> 3.10.72

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 66763546d..1419f8bd1 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -1083,6 +1083,23 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
 		return;
 	}
 
+	/*
+	 * Ignore reports for absolute data if the data didn't change. This is
+	 * not only an optimization but also fixes 'dead' key reports. Some
+	 * RollOver implementations for localized keys (like BACKSLASH/PIPE; HID
+	 * 0x31 and 0x32) report multiple keys, even though a localized keyboard
+	 * can only have one of them physically available. The 'dead' keys
+	 * report constant 0. As all map to the same keycode, they'd confuse
+	 * the input layer. If we filter the 'dead' keys on the HID level, we
+	 * skip the keycode translation and only forward real events.
+	 */
+	if (!(field->flags & (HID_MAIN_ITEM_RELATIVE |
+	                      HID_MAIN_ITEM_BUFFERED_BYTE)) &&
+			      (field->flags & HID_MAIN_ITEM_VARIABLE) &&
+	    usage->usage_index < field->maxusage &&
+	    value == field->value[usage->usage_index])
+		return;
+
 	/* report the usage code as scancode if the key status has changed */
 	if (usage->type == EV_KEY && !!test_bit(usage->code, input->key) != value)
 		input_event(input, EV_MSC, MSC_SCAN, usage->hid);