TV Out on radeon 7500

nikosapi nikosapi at
Sat Oct 20 21:52:09 PDT 2007

On October 17, 2007 01:44:24 you wrote:
> On 10/16/07, nikosapi <nikosapi at> wrote:
> > Hey Alex,
> >
> > Sorry for the late response, I've been busy :(
> >
> > I checked out the latest code from git (2007-10-16 @ 21:30) and tried it
> > out, I now seem to be able to run the following xrandr commands and get
> > an output on the TV:
> >
> > DISPLAY=:0.1
> > xrandr --addmode S-video 800x600
> > xrandr --output S-video --mode 800x600
> > xrandr --output S-video --set tv_standard ntsc
> > xrandr --output S-video --off
> > xrandr --output S-video --mode 800x600
> > # y default DVI-0 seems to be set to 1280x768, which makes the S-video
> > output # the same resolution. I assume this is because the driver mirrors
> > VGA-0 or # DVI-0 on the TV...
> > xrandr --output DVI-0 --mode 800x600
> > # btw, there is nothing but the TV plugged into the card
> >
> > The output of xrandr --verbose before the last command:
> >
> > Here's my Xorg.0.log:
> >
> >
> > Finally I decided to try removing all of the ati card's configuration
> > from my xorg.conf and create a new one just for the radeon card. Then I
> > started a second X server like so:
> >
> > Xorg :1 -config /etc/X11/xorg.conf.radeon -novtswitch -sharevts
> >
> > Then I tried to get the TV output working. When I tried to do:
> >         xrandr --output S-video --mode 800x600
> > xrandr produced the following error:
> >         xrandr: cannot find mode 800x600
> you need to add 800x600 to the server as the driver only adds it when
> it detects a monitor or tv is attached.  Above it's actually adding an
> existing 800x600 mode from another output to the S-video output.
> > * The reason I tried that is because eventually this is how I would like
> > it to * work, I don't want to have two connected desktops, It would be
> > better if I * could have two separate X servers with separate input
> > devices, etc.
> >
> > I looked back at radeon_output.c but I'm really not sure how to enable
> > load detection, sorry I'm not that good of a programmer ;)  If there's a
> > specific way you would like me to test my card let me know, I wouldn't be
> > surprised if I was doing something wrong.
> radeon_output.c ~lines 1776-1782.  basically set data = 1 there so
> load detection will be enabled on all DAC based outputs. then assuming
> load detection works properly, it will detect your TV and
> automatically add and enable 800x600 on the S-video output.  You can
> also try it on the fly with:
> xrandr --output S-video --set load_detection 1
> then try:
> xrandr --output S-video --auto
> and see if it works.
> Alex

Hey Alex!

I finally had more time to play with my video card and I had some success 
tonight thanks to your suggestions! 

I was able to get the TV out working by adding 'data = 1;' on line 1783 and 
now the TV output is detected and works perfectly. I tried using:
	 xrandr --output S-video --set load_detection 1
but it didn't seem to work which is why I ending up making the modification to 
the source code that you described. 

So now, getting the TV output working is as easy as the following:

Xorg :1 -config /etc/X11/xorg.conf.radeon -novtswitch -sharevts
export DISPLAY=:1
xrandr --output S-video --set tv_standard ntsc
xrandr --output S-video --off
xrandr --output S-video --mode 800x600

I had one last question if you don't mind... I noticed that I can't use Xv on 
the TV out, only on the VGA output. Is this a limitation of the 
hardware/driver or is this just another misconfiguration?

Thank you so much for your help and patience,


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