FB Radeon with Apple Cinema Display

Wed May 22 10:15:00 2002

I'm happy to report that FINALLY I can run X-windows on my G4 dual-500 
with ATI Radeon (ADC) card and Apple Cinema Display. It's been a 
looooonnnngggg battle, but I'm finally there!

The only caveat... I can only use 8 bit (palatted) color. Sigh. By the 
way, if anyone is in the same boat and hasn't gotten this working yet, 
e-mail me at willimur@bellatlantic.net and I'd be happy to e-mail you my 
XFree86 configuration file.

I'm trying now to figure out if there's any way to get my coveted 
TrueColor on this system, but there's precious little in terms of 
documentation about how the framebuffer works. Some of the things I've 
had to do...

First, I can only get the system running by booting into linux-novideo 
mode from yaboot. From there I can do a manual "startx". All I really 
had to do was add the screen timings to my XF86Config-4 file. But when I 
try to ask for anything but BitDepth 8 it says it can't find/initialize 
the proper fb mode. I've added entries for both 57 hz and 60 hz (60 is 
what I've seen in all notes on my Internet searches, but 57hz is what's 
mentioned if I do a "fbset -s" command to see what the current frame 
buffer is set at.

Next I tried adding some entries in the /etc/fb.modes file for 57 and 60 
hz at 8, 15, 16, and 24 bit depths. I can do an fbset command with the 
8bit 57hz and 8bit 60hz modes, but I get an ioctl error when I try to do 
the higher bit depths. Additionally, if I try to specify the higher bit 
depths on the fbset command line like 'fbset -depth 8 "1600x1024-57"' 
I'm okay, but if I replace 8 with 16 it dies again.

***strange behavior: if I say "fbset -depth f ..." or even "fbset -depth 
q ..." the command seems to execute, whereas having a double-digit entry 
gives the same error. At first I thought that having "f" work meant it 
was taking the values in hex, but I put the letter q in there (obviously 
illegal) and I got no errors. I'm also noticing that the screen isn't 
flickering or showing any other visible signs of switching modes, so I'm 
doubting that this is working whatsoever.***

Finally, I tried configuring XFree86 for the Radeon (non-fb) driver and 
running it both under my linux-novideo boot and regular linux boot (this 
gives me a blank screen so I had to telnet in from another computer) and 
both locked up the computer.

Does anyone know enough about the Frame Buffer to give me a hint as to 
how I can proceed? I've even dug through the linux source code for the 
Radeon frame buffer just to make sure that TrueColor was supported (it 
is). At this point I'm at a complete loss as to how to set the 
appropriate frame buffer mode.

Thanks

Murray Todd Willams