Comment # 13 on bug 907368 from Andrej Lazo

kernel boot param:

 resume=/dev/sda1 splash=silent quiet showopts video.use_native_backlight=0
acpi_backlight=video
####################################

linux-b4vl:~ # evtest /dev/input/event6
Input driver version is 1.0.1
Input device ID: bus 0x19 vendor 0x0 product 0x0 version 0x0
Input device name: "HP WMI hotkeys"
Supported events:
  Event type 0 (EV_SYN)
  Event type 1 (EV_KEY)
    Event code 138 (KEY_HELP)
    Event code 141 (KEY_SETUP)
    Event code 148 (KEY_PROG1)
    Event code 153 (KEY_DIRECTION)
    Event code 224 (KEY_BRIGHTNESSDOWN)
    Event code 225 (KEY_BRIGHTNESSUP)
    Event code 226 (KEY_MEDIA)
    Event code 240 (KEY_UNKNOWN)
    Event code 358 (KEY_INFO)
  Event type 4 (EV_MSC)
    Event code 4 (MSC_SCAN)
  Event type 5 (EV_SW)
    Event code 1 (SW_TABLET_MODE)
    Event code 5 (SW_DOCK)
Properties:
Testing ... (interrupt to exit)


linux-b4vl:~ # evtest /dev/input/event11
Input driver version is 1.0.1
Input device ID: bus 0x0 vendor 0x0 product 0x0 version 0x0
Input device name: "HDA Intel Headphone"
Supported events:
  Event type 0 (EV_SYN)
  Event type 5 (EV_SW)
    Event code 2 (SW_HEADPHONE_INSERT)
Properties:
Testing ... (interrupt to exit)
^C