[LinuxBIOS] RES: RES: VGA Support on AMD DB800

Omar Esteves Duarte Filho duarte at vonbraunlabs.com.br
Wed Jan 2 12:32:50 CET 2008

Thank you for the support and sorry for the inconvenience, Jordan. You are
right: this is off-topic.

Video is working now and if someone is interested in the solution, please
read below.

After some investigation here, i've finally got VGA output (both text
console and X)! In the end, it seems that there is some problem with the
lxfb driver. I was trying to set up the VGA with the video boot parameter in
the kernel command line ("lxfb.mode_option=..."). But, it did not work.
However, the video output works if "fbset 640x480-60", for instance, was
previously typed. The fbset tool initializes the VGA with different timing
parameters. Below is the VGA timing parameters right after the boot process
is complete and there's still no VGA output:

root at ubuntu-LX800:~# fbset -i

mode "640x480-60"
    # D: 25.175 MHz, H: 31.469 kHz, V: 59.940 Hz
    geometry 640 480 640 480 16
    timings 39682 48 8 25 2 88 2
    rgba 5/11,6/5,5/0,0/0

Then, fbset is used to adjust the video mode:

root at ubuntu-LX800:~# fbset 640x480-60
root at ubuntu-LX800:~#

After that, VGA output works and timing parameters are checked again:

root at ubuntu-LX800:~# fbset -i

mode "640x480-60"
    # D: 25.175 MHz, H: 31.469 kHz, V: 59.940 Hz
    geometry 640 480 640 480 16
    timings 39722 48 16 33 10 96 2
    rgba 5/11,6/5,5/0,0/0

So, I changed the drivers\video\geode\lxfb_core.c file to match the
'working' timing parameters:

const struct fb_videomode geode_modedb[] __initdata = {
	/* 640x480-60 */
	{ NULL, 60, 640, 480, 39722, 48, 16, 33, 10, 96, 2,

Now that video is working, the only issue is the long delay (~90s) between
turning on the platform and getting some video output, which is the time
needed for the kernel to be executed and to load the lxfb driver. I'll try
to speed this up a little bit. 


Omar Esteves Duarte Filho
Embedded Software Engineer
Wernher von Braun Center for Advanced Research
Av. Alice de Castro P. N. Mattosinho, 301
13098-381 Alphaville
Campinas, SP - Brasil
Phone No. +55 19 3262 2207

-----Mensagem original-----
De: Jordan Crouse [mailto:jordan.crouse at amd.com] 
Enviada em: sexta-feira, 28 de dezembro de 2007 19:03
Para: Omar Esteves Duarte Filho
Cc: linuxbios at linuxbios.org
Assunto: Re: RES: VGA Support on AMD DB800

On 26/12/07 10:50 -0200, Omar Esteves Duarte Filho wrote:
> Jordan,
> Thank you again!
> I removed splash and quiet form the menu.lst and added "console=tty0 
> console=ttyS0,115200", as you can see below:
> title           Ubuntu 7.10, kernel
> root            (hd0,0)
> kernel          /boot/vmlinuz-
> root=UUID=a4e4ac87-c677-45e1-a
> a21-1e4654feac95 ro vga=771 console=tty0 console=ttyS0,115200
> initrd          /boot/initrd.img-
> I got some success here: startx works, but there's still no vga 
> console before X starts. I think there is some problem with the lxfb 
> driver because, if i switch the line " Device "AMD" " by "Device 
> "Generic Video Card"" in the xorg.conf file, I get no result. lxfb and 
> fbcon are built into the kernel.

This is starting to get off topic for the linuxbios list, but I'll answer it
here since others might have the same problem.

X and the kernel have nothing to do with one-another - they are completely
seperate entities.  If you do not see the text console (and the penguin)
once the kernel has started, then something has gone wrong.  Please send the
dmesg output from your kernel, and your kernel config.


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