Bug#757356: Apple keyboard: Scan code event (EV_MSC) not generated when the EV_KEY event is generated by hid-apple.c

[Vincent Lefevre <vincent@vinc17.net>]

On 2021-06-02 17:24:38 +0200, Salvatore Bonaccorso wrote:
> Can you, time permitting, starting from there (and needed refreshes)
> try to confirm if the patch solves the issue on top of 5.10.40?

First, the patch did not apply correctly on top of 5.10.46 (currently
in unstable). So I've updated it and attached this new version. (I'm not
sure that the change concerning REL_HWHEEL is needed, but in any case,
it may be safer and it shouldn't hurt, thanks to the "type == EV_KEY"
test.)

Then I couldn't test it because the kernel build fails:

[...]
  CC      fs/locks.o
  CC      fs/binfmt_script.o
  CC      fs/binfmt_elf.o
  CC      fs/compat_binfmt_elf.o
  CC      fs/posix_acl.o
  CC      fs/coredump.o
  CC      fs/drop_caches.o
  CC      fs/fhandle.o
  CC      fs/dcookies.o
  CC [M]  fs/binfmt_misc.o
  CC [M]  fs/mbcache.o
  AR      fs/built-in.a
make[2]: *** [debian/rules:7: build-arch] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2
make[1]: *** [scripts/Makefile.package:77: deb-pkg] Error 2
make: *** [Makefile:1573: deb-pkg] Error 2

I don't know whether this matters, but the /usr/src/linux-source-5.10.tar.xz
archive is not extracted properly by tar, with directories having
incorrect timestamps. I've reported a bug for this:

  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=991275

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

--- a/drivers/hid/hid-apple.c	2021-06-23 12:42:55.000000000 +0000
+++ b/drivers/hid/hid-apple.c	2021-07-19 13:15:39.478215724 +0000
@@ -187,6 +187,15 @@
 	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)
 {
@@ -199,7 +208,8 @@
 
 	if (usage->code == fn_keycode) {
 		asc->fn_on = !!value;
-		input_event(input, usage->type, KEY_FN, value);
+		input_event_with_scancode(input, usage->type, KEY_FN,
+				usage->hid, value);
 		return 1;
 	}
 
@@ -240,7 +250,8 @@
 				code = do_translate ? trans->to : trans->from;
 			}
 
-			input_event(input, usage->type, code, value);
+			input_event_with_scancode(input, usage->type, code,
+					usage->hid, value);
 			return 1;
 		}
 
@@ -258,8 +269,8 @@
 					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;
@@ -270,7 +281,8 @@
 		if (hid->country == HID_COUNTRY_INTERNATIONAL_ISO) {
 			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;
 			}
 		}
@@ -279,7 +291,8 @@
 	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;
 		}
 	}
@@ -287,7 +300,8 @@
 	if (swap_fn_leftctrl) {
 		trans = apple_find_translation(swapped_fn_leftctrl_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;
 		}
 	}
@@ -306,8 +320,8 @@
 
 	if ((asc->quirks & APPLE_INVERT_HWHEEL) &&
 			usage->code == REL_HWHEEL) {
-		input_event(field->hidinput->input, usage->type, usage->code,
-				-value);
+		input_event_with_scancode(field->hidinput->input, usage->type,
+				usage->code, usage->hid, -value);
 		return 1;
 	}