[Bug 23421] dualhead - 2. monitor off (not just blank / black) on radeon; xrandr

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=23421





--- Comment #16 from Alex Deucher <agd5f at yahoo.com>  2009-09-03 07:36:26 PST ---
(In reply to comment #15)
> I have try it.
> 
> IT REALLY WORKS.  GREAT.  Thank You very much !
> 

Excellent.

> Interesting is:
> 
> 1. after reboot from (working) U9.04 in Fedora 11 with "nomodeset" - first time
> ever: both monitors were ON - probably from HW setting from Ubuntu ?!
> 2. with "nomodeset" - the 2. monitor was switched off like usual. But with
> Yours xrandr --addmode ...   it comes up :-)  The dualhead is now working.
> 
> ?? Also after --admode and switching On, xrander reports this output like
> disconnected:

disconnected just means the driver wasn't able to detect a monitor on that
port.  you might try swapping the cables.  Also, if the problematic monitor
uses the secondary dac, you can try:
Option "TVDACLoadDetect" "TRUE"
for the nomodeset case.
Another option is force the output on in your xorg.conf.  See the page I posted
in comment 4.  You'll basically want to add a monitor section with the same
identifier as the output name and with the sync ranges for your monitor and:
Option "Enable" "TRUE"

> 
> 3. After switching to "text" console and back, the monitor goes OFF again. To
> switch it ON is necessary to first switch it off with xrand:
> 
> - xrandr --output VGA-1 --off       and only then --output VGA-1 --mode
> 1024x768
> 
> 4. The names of outputs are contrariwise ?!
> 

Are you saying VGA-0 and VGA-1 switch after a VT switch?  That shouldn't
happen.  Is this with nomodeset or modeset?

> 
> 
> P.S. 
> - How to set mode (resolution, ...) 
> - and dualhead on startup ? 
> - With kernel mode setting ?

using xrandr.  read the guide I posted in comment 4. once you have both outputs
on:
xrandr --output VGA-0 --right-of VGA-1
for example.  If you are using nomodeset, you'll have to specify a virtual
screen large enough for both heads.  in the kms case, the driver will take care
of it automatically.


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