Kevin Charpentier
b504aa05fd
On the ThinkBook 14 G7 ARP (21MV), ideapad-laptop is bound to both the ACPI
device (VPC2004:00) and the WMI device
(8FC0DE0C-B4E4-43FD-B0F3-8871711C1294) at the same time, and both report the
mic mute key into the same input device ("Ideapad extra buttons") a few
milliseconds apart, with different scan codes: 0x8 from the ACPI path and
0x13e from the WMI path.
Userspace applies the toggle twice, so the microphone returns to its previous
state and the key appears not to work at all. Unmapping the WMI scan code
leaves a single event per keypress, and the key then toggles the microphone
reliably, mic mute LED included.
Note this differs from the ThinkBook 16p G5 IRX entry above, where the
duplicate comes from the AT keyboard; here both events originate from
"Ideapad extra buttons" itself.
This was discussed on platform-driver-x86, where the hwdb approach was
suggested in preference to unbinding the WMI driver.
Files in this directory specify a description of hardware devices, in the form of mappings from modalias-like keys (which identify specific hardware devices) to udev properties. Files in this directory are not read by udev directly. Instead, man:systemd-hwdb(8) compiles them into a binary database. See man:hwdb(7) for an overview of the configuration file format, and man:systemd-udevd.service(8) for a description of the udev daemon. Use 'systemd-analyze cat-config udev/hwdb.d' to display the effective config.