Bug#757356: Scan code event not generated for some keys of the Apple keyboard' from 'Scan code event not generated for some keys of the Appple keyboard

[Daniel Lin]

I was recently annoyed that alt/meta don't generate scancodes when
swap_opt_cmd is on, and patched it (diff attached). This passes the
original scancodes through unmodified, even when the keycodes are
translated (e.g. Fn+F1 sends scancodes for Fn and F1, but keycode for
brightness down). Works for me, though I'm not sure if this is a good
approach overall.

--- a/drivers/hid/hid-apple.c	2017-03-04 01:34:38.655588991 -0500
+++ b/drivers/hid/hid-apple.c	2017-03-04 01:47:08.082599141 -0500
@@ -177,6 +177,15 @@
 	return NULL;
 }
 
+static void input_event_with_scancode(struct input_dev *input,
+		__u8 type, __u16 code, unsigned int hid, __s32 value)
+{
+	if (type == EV_KEY &&
+	    (!test_bit(code, input->key)) == value)
+		input_event(input, EV_MSC, MSC_SCAN, hid);
+	input_event(input, type, code, value);
+}
+
 static int hidinput_apple_event(struct hid_device *hid, struct input_dev *input,
 		struct hid_usage *usage, __s32 value)
 {
@@ -185,7 +194,8 @@
 
 	if (usage->code == KEY_FN) {
 		asc->fn_on = !!value;
-		input_event(input, usage->type, usage->code, value);
+		input_event_with_scancode(input, usage->type, usage->code,
+				usage->hid, value);
 		return 1;
 	}
 
@@ -217,8 +227,8 @@
 				else
 					clear_bit(usage->code, asc->pressed_fn);
 
-				input_event(input, usage->type, trans->to,
-						value);
+				input_event_with_scancode(input, usage->type,
+						trans->to, usage->hid, value);
 
 				return 1;
 			}
@@ -238,8 +248,8 @@
 					clear_bit(usage->code,
 							asc->pressed_numlock);
 
-				input_event(input, usage->type, trans->to,
-						value);
+				input_event_with_scancode(input, usage->type,
+						trans->to, usage->hid, value);
 			}
 
 			return 1;
@@ -250,7 +260,8 @@
 		if (asc->quirks & APPLE_ISO_KEYBOARD) {
 			trans = apple_find_translation(apple_iso_keyboard, usage->code);
 			if (trans) {
-				input_event(input, usage->type, trans->to, value);
+				input_event_with_scancode(input, usage->type,
+						trans->to, usage->hid, value);
 				return 1;
 			}
 		}
@@ -259,7 +270,8 @@
 	if (swap_opt_cmd) {
 		trans = apple_find_translation(swapped_option_cmd_keys, usage->code);
 		if (trans) {
-			input_event(input, usage->type, trans->to, value);
+			input_event_with_scancode(input, usage->type,
+					trans->to, usage->hid, value);
 			return 1;
 		}
 	}