[ltp] LCD panel config

Alex Deucher linux-thinkpad@linux-thinkpad.org
Fri, 10 Mar 2006 09:08:54 -0500

On 3/9/06, Norman Walsh <ndw@nwalsh.com> wrote:
> / "Alex Deucher" <alexdeucher@gmail.com> was heard to say:
> |> Any clues about how to tweak the config so that it's within the panels
> |> parameters would be most appreciated.
> >
> | what sort of setting are you trying to achieve? dualhead? clone mode?
> | CRT only?  if you want to use mergedfb which it looks like you are
> | trying to do, you will need to specify the refresh rates for your
> Well, I can only describe what I'm trying to achieve in terms of the
> visual effect. I've never been able to get my head around all of the
> technical options, which ones are actually available on my hardware,
> and what they each can and can not do. (Pointers to user guides for
> the clueless most appreciated.)
> In order of perceived complexity, I'd like to accomplish at least one
> of the following.
> 1. Display the same image on the laptop LCD and the attached external
>    device (at home, that's either a CRT or most recently an LCD panel;
>    on the road, that's often a projector).

if you want crtc1 to drive both outputs, you can disable mergedfb (set
it the option to false) and use your laptop's video output toggle
(e.g. fn-f7) (you may also have to set the bioshotkeys option to
true).  The alternative is to drive each output with it's own crtc
using mergedfb clone mode.  In this case you'd have to specify
CRT2hsync and CRT2vrefresh and force mergedfb on so that the output
would be active in the event that you started the x server without a
monitor attached.

> 2. Display the same image, as before, but with the additional
>    complication that I'd like the panel to display 1600x1200 even when
>    the external device can only display 1024x768 or even 800x600.

mergedfb clone mode.

> 3. Display different images on the LCD and external device. The way
>    I've usually seen this done is the case where the two screens are
>    logically adjacent and the mouse can cross from one to the other.

mergedfb non-clone mode or "regular" dualhead.  See the radeon man
page or the xinerama howto, google, etc.

> 4. Display as in 3, but with the LCD at 1600x1200 even when the
>    external device is at a lower resolution.

same as 3.

> What I have today is "2". With help from this list, and google, and
> man pages, and a little dumb luck, I've got a configuration that
> appears to work correctly. At home, the 1600x1200 desktop appears on
> my CRT. On the road, I fiddle with the "MetaModes" option in this
> section of my xorg.conf config:
> Section "Device"
>         Identifier  "Card0"
>         Driver      "ati"
>         VendorName  "ATI Technologies Inc"
>         BoardName   "M10 NT [FireGL Mobility T2]"
>         BusID       "PCI:1:0:0"
>         # ndw
>         Option          "MonitorLayout" "LVDS,CRT"
>         Option          "MetaModes" "1600x1200-1600x1200"
> #       Option          "MetaModes" "1600x1200-1024x768"
>         # /ndw
> EndSection
> to switch between 1600x1200 in both places and 1600x1200 on the panel
> and 1024x768 on the projector.
> Niavely, I imagined that when I plugged in the LCD panel, it would
> work just like the current CRT monitor does. But it doesn't, hence my
> original query. It seems to work, but it complains about a signal out
> of range. (Interestingly, the CRT claims it's being driven at
> 87.5kHz/70Hz, which is within the range for the LCD, so I'm simply
> more confused than usual, if that's possible :-)
> | external lcd monitor using the:
> |         #Option     "CRT2HSync"               # [<str>]
> |         #Option     "CRT2VRefresh"            # [<str>]
> | options since those apply to the second crtc in that case.
> And how does one determine which values are correct there?

these are just like the hsync and vrefresh fields in the monitor sections, =
Option "CRT2HSync" "31-60"
Option "CRT2VRefresh" "50-75"
fill in with the settings for your monitor.

> | if you are
> | using "regular" multi-head you would need to create multiple device,
> | monitor, and screen sections.
> I attached my xorg.conf file and Xorg.log files to a previous reply.
> But I'll happily send them again if they will allow you to figure out
> what I'm actually doing :-)

Since X doesn't support dynamic reconfiguration (with the exception of
some xrandr hackery), you'll have to create configs for each


>                                         Be seeing you,
>                                           norm
> --
> Norman Walsh <ndw@nwalsh.com> | Resist the urge to hurry; it will only
> http://nwalsh.com/            | slow you down--Bruce Eckel