[ltp] F7 Video Switching on a T42?

[Marius Gedminas]

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On Tue, Mar 14, 2006 at 01:52:53PM -0500, Alex Deucher wrote:
> On 3/14/06, Guarded Identity <q507ddf02@sneakemail.com> wrote:
> > Hi all,
> >
> > I'm pretty dedicated to Debian, but to play around with an application =
that
> > was brutally Debian-unfriendly (Intel's VTune), I installed some versio=
n of
> > SUSE on a USB drive I had.  SUSE pre-configured my T42 pretty nicely.  =
One
> > thing that was caught me off guard was that the F7 video toggling actua=
lly
> > seemed to work.  I had pretty much given up on this with Debian.  Actua=
lly,
> > multi-head in X.org isn't exactly smooth-sailing even without the hotkey
> > toggling, but SUSE seems to have it all rolled out rather nicely.
> >
> > Has anyone figured out how SUSE does it (specifically F7 toggling)?  Is=
 it a
> > kernel hack (maybe to the ibm_acpi module)?  Most solutions that exist =
for
> > other distributions are able to be ported into Debian, but I'm not sure=
 about
> > this one.
>=20
> The fn-F7 video toggling is handled by the bios unless you explicitly
> tell ibm_acpi to handle the fn events directly.  In that case they
> just show up as acpi events that can be hooked to an application or
> script.  Xorg doesn't currently support dynamic output switching so I
> assume either the bios is handling the fn events directly or perhaps
> acpi-video has some sort of interface that uses the bios to toggle the
> outputs what is hooked into the fn events produced by ibm_acpi.

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.

On my T42 the default is CRT + LCD, and I got a working clone mode without =
any
special configuration, so I never bothered with ACPI scripts.

(Nowadays I use MergedFB for true dual-head mode, and I can switch between
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.)


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
              driver  does not support ACPI, there is no way to validate mo=
des
              on an output switch and the BIOS can potentially  change  thi=
ngs
              behind the driver=92s back.  The default is off.

I've never tried it.

Marius Gedminas
--=20
To stay awake all night adds a day to your life.
		-- Stilgar (Frank Herbert _Children_of_Dune_)

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