[PATCH] Input: i8042 - add nomux quirk for Fujitsu LIFEBOOK U7410

[PATCH] Input: i8042 - add nomux quirk for Fujitsu LIFEBOOK U7410

[Lovekesh Solanki]

On the Fujitsu LIFEBOOK U7410 the internal keyboard and touchpad die
shortly after boot if i8042 multiplexing controller is probed and
switched to muxed mode. These multiplexing setup commands disturb the EC
emulated keyboard and atkbd reports "Spurious ACK" and "Unknown key
pressed" warnings, after which both keyboard and touchpad stop
delivering events. Both touchpad and keyboard work in BIOS and GRUB.

Disabling multiplexer using i8042.nomux=1 makes both devices work on
warm/cold boot.

Add a DMI quirk to force nomux mode for this model.

Reported-by: Heiko Brey <cico0815@gmx.de>
Link: https://lore.kernel.org/all/89f36f3f5e4c2d07b9ff72bc0b355875c336e498.camel@gmx.de/
Signed-off-by: Lovekesh Solanki <lovekeshsolanki00@gmail.com>
---
 drivers/input/serio/i8042-acpipnpio.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/serio/i8042-acpipnpio.h b/drivers/input/serio/i8042-acpipnpio.h
index 9ecb0eed48c4..edd9f2e7c65e 100644
--- a/drivers/input/serio/i8042-acpipnpio.h
+++ b/drivers/input/serio/i8042-acpipnpio.h
@@ -664,6 +664,15 @@ static const struct dmi_system_id i8042_dmi_quirk_table[] __initconst = {
 		},
 		.driver_data = (void *)(SERIO_QUIRK_NOAUX)
 	},
+	{
+		/* Fujitsu LIFEBOOK U7410 */
+		/* Mux mode also disturbs the EC keyboard, causing spurious ACKs */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU CLIENT COMPUTING LIMITED"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK U7410"),
+		},
+		.driver_data = (void *)(SERIO_QUIRK_NOMUX)
+	},
 	{
 		/* Gigabyte M912 */
 		.matches = {
-- 
2.55.0

Re: [PATCH] Input: i8042 - add nomux quirk for Fujitsu LIFEBOOK U7410

[Dmitry Torokhov]

On Sun, Sep 20, 2026 at 05:05:41PM +0530, Lovekesh Solanki wrote:
> On the Fujitsu LIFEBOOK U7410 the internal keyboard and touchpad die
> shortly after boot if i8042 multiplexing controller is probed and
> switched to muxed mode. These multiplexing setup commands disturb the EC
> emulated keyboard and atkbd reports "Spurious ACK" and "Unknown key
> pressed" warnings, after which both keyboard and touchpad stop
> delivering events. Both touchpad and keyboard work in BIOS and GRUB.
> 
> Disabling multiplexer using i8042.nomux=1 makes both devices work on
> warm/cold boot.
> 
> Add a DMI quirk to force nomux mode for this model.
> 
> Reported-by: Heiko Brey <cico0815@gmx.de>
> Link: https://lore.kernel.org/all/89f36f3f5e4c2d07b9ff72bc0b355875c336e498.camel@gmx.de/
> Signed-off-by: Lovekesh Solanki <lovekeshsolanki00@gmail.com>

Applied, thank you.

-- 
Dmitry