On Mon, May 31, 2004 at 04:57:29PM +0100, Paul Gotch wrote: > >> I'm afraid I don't know enough about the Radeon driver to say whether > >> this is a driver bug or not. Is the card being diddled in a way the > >> driver cannot detect or work around? > > >Impossible to tell without seeing the X server log. > > I don't believe so, I believe this is actually expected behaviour. As far as > I can tell this is what is happening. > > 1) From reset the card tries to decided what is connected to both the ports. > > 2) If a display is connected to the DVI port that becomes the primary > display and the VGA port the secondary display. Else the VGA port is the > primary and the DVI port is not enabled. > > 3) If dual head is then forcibly enabled when it doesn't think that there is > anything connected to the second display it comes up in clone mode. This is > either undocumented behaviour or is a default in the Radeon driver if the > card has failed to autodected over the the DCC connection to the monitor. > > In my case I believe the problem was caused by the a KVM switch between the > card and the monitor. DCC seems to be very flaky :/ > > The workaround of putting the MonitorLayout option just forces the card > into a particular mode so it ignores whatever is comming over the DCC. > > I've heard it is possible to damage the card with an incorrect MonitorLayout > line but I can't think of a physical mechanism for this actually happening. > > I therefore think that this is worthy of a mention in the documentation for > the radeon driver but is not actually a bug. It might warrent some more > investigation in the radeon driver to see if my hypothesis is correct. Mr. Gotch, do you mind if I use this text in the Debian X FAQ? You can find the current version of the FAQ, complete with its copyright and licensing information, at the following URL: http://necrotic.deadbeast.net/xsf/XFree86/trunk/debian/local/FAQ.xhtml -- G. Branden Robinson | To stay young requires unceasing Debian GNU/Linux | cultivation of the ability to branden@debian.org | unlearn old falsehoods. http://people.debian.org/~branden/ | -- Robert Heinlein
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