Symbol: THINKPAD_EVENT_BRIGHTNESS_UP
sys/dev/acpica/acpi_thinkpad/acpi_thinkpad.c
1452
case THINKPAD_EVENT_BRIGHTNESS_UP:
sys/dev/acpica/acpi_thinkpad/acpi_thinkpad.c
1461
val = (arg == THINKPAD_EVENT_BRIGHTNESS_UP) ? val + 1 : val - 1;