HID: apple: Fix stuck function keys when using FN

This fixes an issue in which key down events for function keys would be
repeatedly emitted even after the user has raised the physical key. For
example, the driver fails to emit the F5 key up event when going through
the following steps:
- fnmode=1: hold FN, hold F5, release FN, release F5
- fnmode=2: hold F5, hold FN, release F5, release FN

The repeated F5 key down events can be easily verified using xev.
Signed-off-by: Joao Moreno <mail@joaomoreno.com>
Co-developed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

drivers/hid/hid-apple.c

@@ -54,7 +54,6 @@ MODULE_PARM_DESC(swap_opt_cmd, "Swap the Option (\"Alt\") and Command (\"Flag\")
 struct apple_sc {
 	unsigned long quirks;
 	unsigned int fn_on;
-	DECLARE_BITMAP(pressed_fn, KEY_CNT);
 	DECLARE_BITMAP(pressed_numlock, KEY_CNT);
 };
 
@@ -181,6 +180,8 @@ static int hidinput_apple_event(struct hid_device *hid, struct input_dev *input,
 {
 	struct apple_sc *asc = hid_get_drvdata(hid);
 	const struct apple_key_translation *trans, *table;
+	bool do_translate;
+	u16 code = 0;
 
 	if (usage->code == KEY_FN) {
 		asc->fn_on = !!value;
@@ -189,8 +190,6 @@ static int hidinput_apple_event(struct hid_device *hid, struct input_dev *input,
 	}
 
 	if (fnmode) {
-		int do_translate;
-
 		if (hid->product >= USB_DEVICE_ID_APPLE_WELLSPRING4_ANSI &&
 				hid->product <= USB_DEVICE_ID_APPLE_WELLSPRING4A_JIS)
 			table = macbookair_fn_keys;
@@ -202,25 +201,33 @@ static int hidinput_apple_event(struct hid_device *hid, struct input_dev *input,
 		trans = apple_find_translation (table, usage->code);
 
 		if (trans) {
-			if (test_bit(usage->code, asc->pressed_fn))
-				do_translate = 1;
-			else if (trans->flags & APPLE_FLAG_FKEY)
-				do_translate = (fnmode == 2 && asc->fn_on) ||
-					(fnmode == 1 && !asc->fn_on);
-			else
-				do_translate = asc->fn_on;
-
-			if (do_translate) {
-				if (value)
-					set_bit(usage->code, asc->pressed_fn);
-				else
-					clear_bit(usage->code, asc->pressed_fn);
-
-				input_event(input, usage->type, trans->to,
-						value);
-
-				return 1;
+			if (test_bit(trans->from, input->key))
+				code = trans->from;
+			else if (test_bit(trans->to, input->key))
+				code = trans->to;
+
+			if (!code) {
+				if (trans->flags & APPLE_FLAG_FKEY) {
+					switch (fnmode) {
+					case 1:
+						do_translate = !asc->fn_on;
+						break;
+					case 2:
+						do_translate = asc->fn_on;
+						break;
+					default:
+						/* should never happen */
+						do_translate = false;
+					}
+				} else {
+					do_translate = asc->fn_on;
+				}
+
+				code = do_translate ? trans->to : trans->from;
 			}
+
+			input_event(input, usage->type, code, value);
+			return 1;
 		}
 
 		if (asc->quirks & APPLE_NUMLOCK_EMULATION &&