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-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
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