[PATCH RFC 1/2] platform/x86: ideapad-laptop: Ignore keyboard backlight hotkeys

[Ciro Pedrini via B4 Relay]

From: Ciro Pedrini <ciro.pedrini@xxxxxxxxx>

On the Legion Pro 7 16IAX10H, Fn+Space (backlight effect), Fn+Up and
Fn+Down (backlight brightness) emit WMI fn-key events 0x21, 0x1a and
0x19, which the keymap does not cover, so they reach userspace as
KEY_UNKNOWN. The keyboard's USB controller handles these keys itself: it
switches the effect or changes the brightness, and reports the new level
on its own HID interface. Ignore the three events, as is already done for
FnLock and Esc, rather than mapping them to KEY_KBDILLUM*, which would
make userspace change the brightness a second time.

Tested on the 16IAX10H with 7.2: with the change, evtest shows no events
for the three keys, and the keyboard still switches the effect and the
brightness.

The change and this changelog were prepared with Claude Code (Claude
Opus 5.5), from measurements on the laptop (evtest on the "Ideapad
extra buttons" device); I reviewed and tested them.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Ciro Pedrini <ciro.pedrini@xxxxxxxxx>
---
 drivers/platform/x86/lenovo/ideapad-laptop.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/platform/x86/lenovo/ideapad-laptop.c b/drivers/platform/x86/lenovo/ideapad-laptop.c
index 91a8d11c79c5..8b6c08b21c8d 100644
--- a/drivers/platform/x86/lenovo/ideapad-laptop.c
+++ b/drivers/platform/x86/lenovo/ideapad-laptop.c
@@ -1336,6 +1336,10 @@ static const struct key_entry ideapad_keymap[] = {
 	{ KE_IGNORE,	0x02 | IDEAPAD_WMI_KEY },
 	/* Esc (handled by the firmware) */
 	{ KE_IGNORE,	0x03 | IDEAPAD_WMI_KEY },
+	/* Keyboard backlight down, up and effect (handled by the keyboard) */
+	{ KE_IGNORE,	0x19 | IDEAPAD_WMI_KEY },
+	{ KE_IGNORE,	0x1a | IDEAPAD_WMI_KEY },
+	{ KE_IGNORE,	0x21 | IDEAPAD_WMI_KEY },
 	/* Customizable Lenovo Hotkey ("star" with 'S' inside) */
 	{ KE_KEY,	0x01 | IDEAPAD_WMI_KEY, { KEY_FAVORITES } },
 	{ KE_KEY,	0x04 | IDEAPAD_WMI_KEY, { KEY_SELECTIVE_SCREENSHOT } },

-- 
2.56.0