218 lines
7.9 KiB
Plaintext
218 lines
7.9 KiB
Plaintext
CyBlaFB is a framebuffer driver for the Cyberblade/i1 graphics core integrated
|
|
into the VIA Apollo PLE133 (aka vt8601) south bridge. It is developed and
|
|
tested using a VIA EPIA 5000 board.
|
|
|
|
Cyblafb - compiled into the kernel or as a module?
|
|
==================================================
|
|
|
|
You might compile cyblafb either as a module or compile it permanently into the
|
|
kernel.
|
|
|
|
Unless you have a real reason to do so you should not compile both vesafb and
|
|
cyblafb permanently into the kernel. It's possible and it helps during the
|
|
developement cycle, but it's useless and will at least block some otherwise
|
|
usefull memory for ordinary users.
|
|
|
|
Selecting Modes
|
|
===============
|
|
|
|
Startup Mode
|
|
============
|
|
|
|
First of all, you might use the "vga=???" boot parameter as it is
|
|
documented in vesafb.txt and svga.txt. Cyblafb will detect the video
|
|
mode selected and will use the geometry and timings found by
|
|
inspecting the hardware registers.
|
|
|
|
video=cyblafb vga=0x317
|
|
|
|
Alternatively you might use a combination of the mode, ref and bpp
|
|
parameters. If you compiled the driver into the kernel, add something
|
|
like this to the kernel command line:
|
|
|
|
video=cyblafb:1280x1024,bpp=16,ref=50 ...
|
|
|
|
If you compiled the driver as a module, the same mode would be
|
|
selected by the following command:
|
|
|
|
modprobe cyblafb mode=1280x1024 bpp=16 ref=50 ...
|
|
|
|
None of the modes possible to select as startup modes are affected by
|
|
the problems described at the end of the next subsection.
|
|
|
|
For all startup modes cyblafb chooses a virtual x resolution of 2048,
|
|
the only exception is mode 1280x1024 in combination with 32 bpp. This
|
|
allows ywrap scrolling for all those modes if rotation is 0 or 2, and
|
|
also fast scrolling if rotation is 1 or 3. The default virtual y reso-
|
|
lution is 4096 for bpp == 8, 2048 for bpp==16 and 1024 for bpp == 32,
|
|
again with the only exception of 1280x1024 at 32 bpp.
|
|
|
|
Please do set your video memory size to 8 Mb in the Bios setup. Other
|
|
values will work, but performace is decreased for a lot of modes.
|
|
|
|
Mode changes using fbset
|
|
========================
|
|
|
|
You might use fbset to change the video mode, see "man fbset". Cyblafb
|
|
generally does assume that you know what you are doing. But it does
|
|
some checks, especially those that are needed to prevent you from
|
|
damaging your hardware.
|
|
|
|
- only 8, 16, 24 and 32 bpp video modes are accepted
|
|
- interlaced video modes are not accepted
|
|
- double scan video modes are not accepted
|
|
- if a flat panel is found, cyblafb does not allow you
|
|
to program a resolution higher than the physical
|
|
resolution of the flat panel monitor
|
|
- cyblafb does not allow vclk to exceed 230 MHz. As 32 bpp
|
|
and (currently) 24 bit modes use a doubled vclk internally,
|
|
the dotclock limit as seen by fbset is 115 MHz for those
|
|
modes and 230 MHz for 8 and 16 bpp modes.
|
|
- cyblafb will allow you to select very high resolutions as
|
|
long as the hardware can be programmed to these modes. The
|
|
documented limit 1600x1200 is not enforced, but don't expect
|
|
perfect signal quality.
|
|
|
|
Any request that violates the rules given above will be either changed
|
|
to something the hardware supports or an error value will be returned.
|
|
|
|
If you program a virtual y resolution higher than the hardware limit,
|
|
cyblafb will silently decrease that value to the highest possible
|
|
value. The same is true for a virtual x resolution that is not
|
|
supported by the hardware. Cyblafb tries to adapt vyres first because
|
|
vxres decides if ywrap scrolling is possible or not.
|
|
|
|
Attempts to disable acceleration are ignored, I believe that this is
|
|
safe.
|
|
|
|
Some video modes that should work do not work as expected. If you use
|
|
the standard fb.modes, fbset 640x480-60 will program that mode, but
|
|
you will see a vertical area, about two characters wide, with only
|
|
much darker characters than the other characters on the screen.
|
|
Cyblafb does allow that mode to be set, as it does not violate the
|
|
official specifications. It would need a lot of code to reliably sort
|
|
out all invalid modes, playing around with the margin values will
|
|
give a valid mode quickly. And if cyblafb would detect such an invalid
|
|
mode, should it silently alter the requested values or should it
|
|
report an error? Both options have some pros and cons. As stated
|
|
above, none of the startup modes are affected, and if you set
|
|
verbosity to 1 or higher, cyblafb will print the fbset command that
|
|
would be needed to program that mode using fbset.
|
|
|
|
|
|
Other Parameters
|
|
================
|
|
|
|
|
|
crt don't autodetect, assume monitor connected to
|
|
standard VGA connector
|
|
|
|
fp don't autodetect, assume flat panel display
|
|
connected to flat panel monitor interface
|
|
|
|
nativex inform driver about native x resolution of
|
|
flat panel monitor connected to special
|
|
interface (should be autodetected)
|
|
|
|
stretch stretch image to adapt low resolution modes to
|
|
higer resolutions of flat panel monitors
|
|
connected to special interface
|
|
|
|
center center image to adapt low resolution modes to
|
|
higer resolutions of flat panel monitors
|
|
connected to special interface
|
|
|
|
memsize use if autodetected memsize is wrong ...
|
|
should never be necessary
|
|
|
|
nopcirr disable PCI read retry
|
|
nopciwr disable PCI write retry
|
|
nopcirb disable PCI read bursts
|
|
nopciwb disable PCI write bursts
|
|
|
|
bpp bpp for specified modes
|
|
valid values: 8 || 16 || 24 || 32
|
|
|
|
ref refresh rate for specified mode
|
|
valid values: 50 <= ref <= 85
|
|
|
|
mode 640x480 or 800x600 or 1024x768 or 1280x1024
|
|
if not specified, the startup mode will be detected
|
|
and used, so you might also use the vga=??? parameter
|
|
described in vesafb.txt. If you do not specify a mode,
|
|
bpp and ref parameters are ignored.
|
|
|
|
verbosity 0 is the default, increase to at least 2 for every
|
|
bug report!
|
|
|
|
Development hints
|
|
=================
|
|
|
|
It's much faster do compile a module and to load the new version after
|
|
unloading the old module than to compile a new kernel and to reboot. So if you
|
|
try to work on cyblafb, it might be a good idea to use cyblafb as a module.
|
|
In real life, fast often means dangerous, and that's also the case here. If
|
|
you introduce a serious bug when cyblafb is compiled into the kernel, the
|
|
kernel will lock or oops with a high probability before the file system is
|
|
mounted, and the danger for your data is low. If you load a broken own version
|
|
of cyblafb on a running system, the danger for the integrity of the file
|
|
system is much higher as you might need a hard reset afterwards. Decide
|
|
yourself.
|
|
|
|
Module unloading, the vfb method
|
|
================================
|
|
|
|
If you want to unload/reload cyblafb using the virtual framebuffer, you need
|
|
to enable vfb support in the kernel first. After that, load the modules as
|
|
shown below:
|
|
|
|
modprobe vfb vfb_enable=1
|
|
modprobe fbcon
|
|
modprobe cyblafb
|
|
fbset -fb /dev/fb1 1280x1024-60 -vyres 2662
|
|
con2fb /dev/fb1 /dev/tty1
|
|
...
|
|
|
|
If you now made some changes to cyblafb and want to reload it, you might do it
|
|
as show below:
|
|
|
|
con2fb /dev/fb0 /dev/tty1
|
|
...
|
|
rmmod cyblafb
|
|
modprobe cyblafb
|
|
con2fb /dev/fb1 /dev/tty1
|
|
...
|
|
|
|
Of course, you might choose another mode, and most certainly you also want to
|
|
map some other /dev/tty* to the real framebuffer device. You might also choose
|
|
to compile fbcon as a kernel module or place it permanently in the kernel.
|
|
|
|
I do not know of any way to unload fbcon, and fbcon will prevent the
|
|
framebuffer device loaded first from unloading. [If there is a way, then
|
|
please add a description here!]
|
|
|
|
Module unloading, the vesafb method
|
|
===================================
|
|
|
|
Configure the kernel:
|
|
|
|
<*> Support for frame buffer devices
|
|
[*] VESA VGA graphics support
|
|
<M> Cyberblade/i1 support
|
|
|
|
Add e.g. "video=vesafb:ypan vga=0x307" to the kernel parameters. The ypan
|
|
parameter is important, choose any vga parameter you like as long as it is
|
|
a graphics mode.
|
|
|
|
After booting, load cyblafb without any mode and bpp parameter and assign
|
|
cyblafb to individual ttys using con2fb, e.g.:
|
|
|
|
modprobe cyblafb
|
|
con2fb /dev/fb1 /dev/tty1
|
|
|
|
Unloading cyblafb works without problems after you assign vesafb to all
|
|
ttys again, e.g.:
|
|
|
|
con2fb /dev/fb0 /dev/tty1
|
|
rmmod cyblafb
|