ubuntu-x-swat team mailing list archive

[Chris Halse Rogers <raof@xxxxxxxxxx>]

Ok.  When xrandr turns off the LVDS display, the *only* thing it does is
set the LVDS' CRTC to "off".

Tracing through gnome-desktop's RANDR code, on the other hand, we have:
0) Grab the server
1) First, set all CRTCs to off.
2) Now, foreach output, assign the first valid CRTC to it
2*) If some outputs did not have a valid CRTC, bail
3) Set each CRTC to the appropriate mode, attached to the appropriate output
4) Ungrab the server.

This would appear to have two results:
1) gnome-desktop can reject valid setups should there be a CRTC with restrictions on which outputs it can drive (which is extremely common), and
2) gnome-desktop does a whole lot of unnecessary work on modeswitch.

Somewhere in that extra work, something is going wrong.  I'm not
entirely sure what it is, though.  One of the side-effects is that
disabling the LVDS will cause gnome-desktop to drive the external
display with a different CRTC, but xrandr happily switches between
different CRTCs on my external display…

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You received this bug notification because you are a member of Ubuntu-X,
which is subscribed to xserver-xorg-video-intel in Ubuntu.
https://bugs.launchpad.net/bugs/861426

Title:
  [Oneiric] [Regression] When disabling onboard LVDS display and just
  using external VGA screen corruption occurs

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