[ltp] T420 /proc/acpi/ibm/video not working

David Woodfall linux-thinkpad@linux-thinkpad.org
Sat, 7 Feb 2015 12:14:45 +0000

>When I cat /proc/acpi/ibm/video it shows every monitor disabled, even when
>int and ext are on.
>Echoing anything there has no effect at all. It all worked fine in my
>T42. What I would like to do is just use the video_switch command.
>Is this a known problem, and is there a workaround?

Sorry, I posted in haste. When I say 'int' and 'ext' I mean LCD and


# cat /proc/acpi/ibm/video
status:         supported
lcd:            disabled
crt:            disabled
dvi:            disabled
auto:           disabled
commands:       lcd_enable, lcd_disable
commands:       crt_enable, crt_disable
commands:       dvi_enable, dvi_disable
commands:       auto_enable, auto_disable
commands:       video_switch, expand_toggle

Linux 3.13.5

I'm currently upgrading to last stable kernel to see if there's a