Microphone mute Fn hotkey does not work on Dell Latitude 7370

[Michael Doube]

Mic mute hotkey (Fn+F4)on Dell Latitude 7370 does not work. It generates a correct keycode but this is not translated into 'action'. Mic mute can be activated in software by ticking the mute checkbox, and this correctly activates the mic mute key's LED.

Also present in Zesty daily ISO.

:~$ acpi_listen
button/micmute MICMUTE 00000080 00000000 K
 PNP0C14:01 000000d0 00000000

:~$ sudo showkey -k
keycode 248 press
keycode 248 release

:~$ sudo evtest
No device specified, trying to scan all of /dev/input/event*
Available devices:
/dev/input/event0: Lid Switch
/dev/input/event1: Power Button
/dev/input/event2: Sleep Button
/dev/input/event3: Power Button
/dev/input/event4: AT Translated Set 2 keyboard
/dev/input/event5: Video Bus
/dev/input/event6: AlpsPS/2 ALPS DualPoint Stick
/dev/input/event7: AlpsPS/2 ALPS DualPoint TouchPad
/dev/input/event8: DELL Wireless hotkeys
/dev/input/event9: ELAN Touchscreen
/dev/input/event10: Integrated_Webcam_HD
/dev/input/event11: HDA Intel PCH Headphone Mic
/dev/input/event12: HDA Intel PCH HDMI/DP,pcm=3
/dev/input/event13: HDA Intel PCH HDMI/DP,pcm=7
/dev/input/event14: HDA Intel PCH HDMI/DP,pcm=8
/dev/input/event15: Dell WMI hotkeys
Select the device event number [0-15]: 15
Input driver version is 1.0.1
Input device ID: bus 0x19 vendor 0x0 product 0x0 version 0x0
Input device name: "Dell WMI hotkeys"
Supported events:
  Event type 0 (EV_SYN)
  Event type 1 (EV_KEY)
    Event code 113 (KEY_MUTE)
    Event code 114 (KEY_VOLUMEDOWN)
    Event code 115 (KEY_VOLUMEUP)
    Event code 148 (KEY_PROG1)
    Event code 149 (KEY_PROG2)
    Event code 161 (KEY_EJECTCD)
    Event code 202 (KEY_PROG3)
    Event code 203 (KEY_PROG4)
    Event code 224 (KEY_BRIGHTNESSDOWN)
    Event code 225 (KEY_BRIGHTNESSUP)
    Event code 227 (KEY_SWITCHVIDEOMODE)
    Event code 236 (KEY_BATTERY)
    Event code 240 (KEY_UNKNOWN)
    Event code 248 (KEY_MICMUTE)
    Event code 431 (KEY_DISPLAYTOGGLE)
  Event type 4 (EV_MSC)
    Event code 4 (MSC_SCAN)
Properties:
Testing ... (interrupt to exit)
Event: time 1483869894.006318, type 4 (EV_MSC), code 4 (MSC_SCAN), value 100150
Event: time 1483869894.006318, type 1 (EV_KEY), code 248 (KEY_MICMUTE), value 1
Event: time 1483869894.006318, -------------- SYN_REPORT ------------
Event: time 1483869894.006416, type 1 (EV_KEY), code 248 (KEY_MICMUTE), value 0
Event: time 1483869894.006416, -------------- SYN_REPORT ------------

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: udev 229-4ubuntu13
Uname: Linux 4.9.0-040900-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.4
Architecture: amd64
CurrentDesktop: Unity
CustomUdevRuleFiles: 80-canon_mfp2.rules
Date: Sun Jan 8 10:07:22 2017
InstallationDate: Installed on 2016-05-15 (238 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
MachineType: Dell Inc. Latitude 7370
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.9.0-040900-generic root=UUID=d96256e6-13a6-46a5-ba80-2e121d8f8dab ro quiet splash vt.handoff=7
SourcePackage: systemd
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/31/2016
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.9.3
dmi.board.name: 0MMWGJ
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.9.3:bd10/31/2016:svnDellInc.:pnLatitude7370:pvr:rvnDellInc.:rn0MMWGJ:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude 7370
dmi.sys.vendor: Dell Inc.

[Kai-Heng Feng (kaihengfeng)]

https://github.com/systemd/systemd/pull/5012

I tested this on the Latitude 7370 on Zesty daily iso, and it works.

[Michael Doube (michael-doube)]

I tested this just now using the Zesty daily iso, and my mic mute button doesn't mute the mic. I see in my log:

Jan 9 10:46:18 ubuntu systemd-udevd[1086]: Error calling EVIOCSKEYCODE on device node '/dev/input/event15' (scan code 0x150, key code 190): Invalid argument

Which is the same one referenced in the pull request above.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Taihsiang Ho (tai271828)]

I have tested the fix suggested in the comment #2, and verify that the fix works on Ubuntu Yakkety (tested with kernel 4.8.0-34).

Steps to verify:
1. edit the hwdb (/lib/udev/hwdb.d/60-keyboard.hwdb) suggested as https://github.com/systemd/systemd/pull/5012
2. compile the hwdb by "sudo systemd-hwdb update" (or "sudo systemd-hwdb update --usr")
3. reboot
4. now the fn+f4 should work to mute the mic.

[dastillero (dastillero)]

Fix described on Comment #2 is working for me too on a Dell Latitude 3150.

Thanks!