Re: Getting Dual Independent Heads to work on Debian(sid) on iBook

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> hing is ok. 
> 
> 2. On the iBook if I set both BusID's in both device sections to 0:10:0
> then X won't startup even though this is the ID reported by lspci for
> the ATI chip. If I just set the BusID in the device section associated
> with the external CRT to 0:10:0 then X will start and the colors are ok
> but there are scrolling lines in the lcd panel. Also, if I run glxinfo
> then it reports information on just one screen even though I have
> defined two of them.

I think lspci has hexadecimal output while XF86Config expects decimal,
try 0:16:0

> 3. If both are set to BusID 0:16:0 (or just the device section
> associated with the external CRT) then X starts but both screens are
> yellowish and there are scrolling lines in the lcd panel. Also, if I run
> glxinfo then it reports information on two screens (as I expect).

First get the native modeline of your panel with fbset -x before you
launch X and make sure X uses that for the panel.

Also, there is a problem with the LCD panel on some iBooks, possibly
yours. On these, for an unknown reason, the PLL values we calcule
provide a flickering display. I have hard coded values in radeonfb
but of course that's not a solution for you. Keeping the firmware set
values would work too if XFree driver can be instructed to do that.

I'm not too sure how to solve that last problem properly. The
interesting fact is that if I use the same PLL values as MacOS uses,
I also have flickering display. So there is something else that is
interfering with the PLL in some way. It seems though that MacOS
reconfigure the MPLL and SPLL (to obtain the same final clocks but
using a different pair of dividers), there might be something related
to the flickering in there... Only ATI can tell.
 
> >From previous mailing list responses around this issue and my test
> results so far I have thought that further development work is required
> on the radeon XFree86 4.3.0 drivers in order to properly enable this
> dual-headed mode on the iBook and relieve some of the other odd issues
> defined above.
>
> Any help in pointing me in the right direction as far as changes
> required etc. with the driver(s) would be appreciated.
> 
> -dean andreakis
-- 
Benjamin Herrenschmidt <benh@kernel.crashing.org>