[ltp] Re: RFC: removal of video output switching from thinkpad-acpi

[Alex Deucher]

On Feb 20, 2008 2:11 AM, Elias Oltmanns <eo@nebensachen.de> wrote:
> Henrique de Moraes Holschuh <hmh@hmh.eng.br> wrote:
> > On Tue, 19 Feb 2008, Paul Fox wrote:
> >> henrique de moraes holschuh wrote:
> [...]
> >>  > The question is: does the video output stuff in thinkpad-acpi works well
> >>  > enough in the X41 to justify its continued existence?
> >>
> >> well, it at least lets me switch from one screen to the other
> >> with video_switch.  i know of no other way to enable the CRT.
> >> is there?
>
> As I found out only this weekend, there is (on my X40 at least). If I
> mask this hotkey, so thinkpad-acpi won't handle it, and if I prevent my
> system from loading the video module, then I can switch to and from CRT.
> Mind you, there is no way to enable CRT and LCD at the same time.
>

This is a hw/bios implementation limitation.  The same crtc can't
drive both VGA and LVDS at the same time.

> >
> > ACPI video, in some thinkpads. But since most ACPI firmwares are
> >completely
> > and utterly broken on that area, upstream removed that function from ACPI
> > video very recently.
> >
> > It looks like I will have to work on thinkpad-acpi video control, and port
> > it to sysfs :(
>
> Well, I for one would greatly appreciate that since I use scripts for
> automated video switching on a regular basis.

If you are using X, this is not a good idea.  stick to xrandr.

Alex