[LinuxBIOS] RES: RES: RES: VGA Support on AMD DB800
Omar Esteves Duarte Filho
duarte at vonbraunlabs.com.br
Wed Jan 2 20:36:08 CET 2008
>
> First - please - stop using the term 'VGA'. VGA is a very
> specific standard for video display
> (http://en.wikipedia.org/wiki/VGA). There is no VGA here.
> By using the term, you muddle the discussion.
Ok.
>
> mode_option is only valid when you load the driver as a
> module. When running with the driver built in, then you
> specify the mode on the command line,
> as detailed in Documentation/fb/modedb.txt. The correct way
> to specify the
> mode on the command line is as follows:
>
> video=lxfb:<xres>-<yres>-<bpp>@<refresh>
Yes, my fault! Actually, I did use the correct way of specifying the mode on
the command line. However, when composing the email, i wrongly wrote the
'mode_option'.
lxfb driver is compiled into the kernel and the current command line is:
kernel /boot/vmlinuz-2.6.23.9-geodelx-fb
root=UUID=a4e4ac87-c677-45e1-aa21-1e4654feac95 ro console=tty0
console=ttyS0,115200 video=lxfb:640x480 at 60
>
> I also noted that you were specifying vga=<number> on your
> command line - if the vesa framebuffer is also installed in
> your kernel (as it would be with a normal Ubuntu kernel),
> then that will cause the VESA framebuffer to be loaded first
> (which would of course, fail). The lxfb would be loaded as
> well, but registered as the second framebuffer (if you have
> your kernel output from dmesg, you should be able to see this happen).
>
> The fbset you did below would kick the second driver and have
> it take over the console from the failed primary driver.
VESA VGA Support is -not- enabled. So, lxfb is registered as the first
framebuffer (/dev/fb0):
root at ubuntu-LX800:~# cat /proc/fb
0 Geode LX
>
> This is the mode that is listed in the file /etc/fb.modes -
> which is a set of generic timings provided by Ubuntu. Both
> timings are actually correct - if you were to run fbset and
> set the previous timings, they would work. What you are
> seeing is a side effect of a poorly configured kernel.
>
> Jordan
>
I tried to check both timings sets using "fbset --timings" command. The only
set that works is:
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
Endmode
The other set (the "original" one") provides VSYNC=63Hz, instead of 60Hz:
root at ubuntu-LX800:~# fbset -i
mode "640x480-63"
# D: 25.200 MHz, H: 32.143 kHz, V: 63.150 Hz
geometry 640 480 640 480 16
timings 39682 48 8 25 2 88 2
rgba 5/11,6/5,5/0,0/0
Endmode
Omar.
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