[ltp] F7 Video Switching on a T42?

[Alex Deucher]

On 3/14/06, Identity Guarded <d7rjwkw02@sneakemail.com> wrote:
> On Tuesday 14 March 2006 2:58 pm, Marius Gedminas mgedmin-at-b4net.lt |
> Linux-Thinkpad| wrote:
> > On Thinkpads you can perform video switching by doing
> >
> >   echo video_switch > /proc/acpi/ibm/video
> >
> > It is possible to bind that command to the ACPI event generated by
> > Fn-F7.
>
> I remember playing around this.  It didn't work.  If I didn't have acpid
> manage F7 events, then as I remember ibm_acpi would blank my LCD and I
> couldn't figure out a way to get my display back without rebooting the
> machine.
>
> > (Nowadays I use MergedFB for true dual-head mode, and I can switch betw=
een
> > single-head and dual-head with xrandr.  I never had to fiddle with
> > /proc/acpi/ibm/video or Fn-F7 to get output on the external screen, but
> > then again I never wanted "LCD only" or "CRT only" output modes.)
>
> I'm with Shem on this one.  It would be nice to not waste the power drivi=
ng
> an output that's not in use.  The only way I could figure out to cut powe=
r
> from the CRT output is to restart X with the monitor plugged.
>
> > The radeon driver also has an option
> >
> >        Option "BIOSHotkeys" "boolean"
> >               Enable  BIOS  hotkey  output  switching. This allows the =
BIOS
> > to toggle outputs using hotkeys (e.g.,  fn-f7,  etc.).   Since  the dri=
ver
> > does not support ACPI, there is no way to validate modes on an output
> > switch and the BIOS can potentially  change  things behind the driver's
> > back.  The default is off.
>
> I kind of remember reading about this one, but I don't recall messing aro=
und
> with it.  I'll give it a whirl when I have more time.

all this option does is prevent the radeon driver from disabling bios
controlled video events while X is running.

Alex

>
> Thanks for the prompt responses everyone.
>
> - Sukant