xref: /OK3568_Linux_fs/kernel/Documentation/fb/matroxfb.rst (revision 4882a59341e53eb6f0b4789bf948001014eff981)

=================
What is matroxfb?
=================

.. [This file is cloned from VesaFB. Thanks go to Gerd Knorr]


This is a driver for a graphic framebuffer for Matrox devices on
Alpha, Intel and PPC boxes.

Advantages:

 * It provides a nice large console (128 cols + 48 lines with 1024x768)
   without using tiny, unreadable fonts.
 * You can run XF{68,86}_FBDev or XFree86 fbdev driver on top of /dev/fb0
 * Most important: boot logo :-)

Disadvantages:

 * graphic mode is slower than text mode... but you should not notice
   if you use same resolution as you used in textmode.


How to use it?
==============

Switching modes is done using the video=matroxfb:vesa:... boot parameter
or using `fbset` program.

If you want, for example, enable a resolution of 1280x1024x24bpp you should
pass to the kernel this command line: "video=matroxfb:vesa:0x1BB".

You should compile in both vgacon (to boot if you remove you Matrox from
box) and matroxfb (for graphics mode). You should not compile-in vesafb
unless you have primary display on non-Matrox VBE2.0 device (see
Documentation/fb/vesafb.rst for details).

Currently supported video modes are (through vesa:... interface, PowerMac
has [as addon] compatibility code):


Graphic modes
-------------

===  =======  =======  =======  =======  =======
bpp  640x400  640x480  768x576  800x600  960x720
===  =======  =======  =======  =======  =======
  4             0x12             0x102
  8   0x100    0x101    0x180    0x103    0x188
 15            0x110    0x181    0x113    0x189
 16            0x111    0x182    0x114    0x18A
 24            0x1B2    0x184    0x1B5    0x18C
 32            0x112    0x183    0x115    0x18B
===  =======  =======  =======  =======  =======


Graphic modes (continued)
-------------------------

===  ======== ======== ========= ========= =========
bpp  1024x768 1152x864 1280x1024 1408x1056 1600x1200
===  ======== ======== ========= ========= =========
  4    0x104             0x106
  8    0x105    0x190    0x107     0x198     0x11C
 15    0x116    0x191    0x119     0x199     0x11D
 16    0x117    0x192    0x11A     0x19A     0x11E
 24    0x1B8    0x194    0x1BB     0x19C     0x1BF
 32    0x118    0x193    0x11B     0x19B
===  ======== ======== ========= ========= =========


Text modes
----------

==== =======  =======  ========  ========  ========
text 640x400  640x480  1056x344  1056x400  1056x480
==== =======  =======  ========  ========  ========
 8x8   0x1C0    0x108     0x10A     0x10B     0x10C
8x16 2, 3, 7                        0x109
==== =======  =======  ========  ========  ========

You can enter these number either hexadecimal (leading `0x`) or decimal
(0x100 = 256). You can also use value + 512 to achieve compatibility
with your old number passed to vesafb.

Non-listed number can be achieved by more complicated command-line, for
example 1600x1200x32bpp can be specified by `video=matroxfb:vesa:0x11C,depth:32`.


X11
===

XF{68,86}_FBDev should work just fine, but it is non-accelerated. On non-intel
architectures there are some glitches for 24bpp videomodes. 8, 16 and 32bpp
works fine.

Running another (accelerated) X-Server like XF86_SVGA works too. But (at least)
XFree servers have big troubles in multihead configurations (even on first
head, not even talking about second). Running XFree86 4.x accelerated mga
driver is possible, but you must not enable DRI - if you do, resolution and
color depth of your X desktop must match resolution and color depths of your
virtual consoles, otherwise X will corrupt accelerator settings.


SVGALib
=======

Driver contains SVGALib compatibility code. It is turned on by choosing textual
mode for console. You can do it at boot time by using videomode
2,3,7,0x108-0x10C or 0x1C0. At runtime, `fbset -depth 0` does this work.
Unfortunately, after SVGALib application exits, screen contents is corrupted.
Switching to another console and back fixes it. I hope that it is SVGALib's
problem and not mine, but I'm not sure.


Configuration
=============

You can pass kernel command line options to matroxfb with
`video=matroxfb:option1,option2:value2,option3` (multiple options should be
separated by comma, values are separated from options by `:`).
Accepted options:

============ ===================================================================
mem:X        size of memory (X can be in megabytes, kilobytes or bytes)
	     You can only decrease value determined by driver because of
	     it always probe for memory. Default is to use whole detected
	     memory usable for on-screen display (i.e. max. 8 MB).
disabled     do not load driver; you can use also `off`, but `disabled`
	     is here too.
enabled      load driver, if you have `video=matroxfb:disabled` in LILO
	     configuration, you can override it by this (you cannot override
	     `off`). It is default.
noaccel      do not use acceleration engine. It does not work on Alphas.
accel        use acceleration engine. It is default.
nopan        create initial consoles with vyres = yres, thus disabling virtual
	     scrolling.
pan          create initial consoles as tall as possible (vyres = memory/vxres).
	     It is default.
nopciretry   disable PCI retries. It is needed for some broken chipsets,
	     it is autodetected for intel's 82437. In this case device does
	     not comply to PCI 2.1 specs (it will not guarantee that every
	     transaction terminate with success or retry in 32 PCLK).
pciretry     enable PCI retries. It is default, except for intel's 82437.
novga        disables VGA I/O ports. It is default if BIOS did not enable
	     device. You should not use this option, some boards then do not
	     restart without power off.
vga          preserve state of VGA I/O ports. It is default. Driver does not
	     enable VGA I/O if BIOS did not it (it is not safe to enable it in
	     most cases).
nobios       disables BIOS ROM. It is default if BIOS did not enable BIOS
	     itself. You should not use this option, some boards then do not
	     restart without power off.
bios         preserve state of BIOS ROM. It is default. Driver does not enable
	     BIOS if BIOS was not enabled before.
noinit       tells driver, that devices were already initialized. You should use
	     it if you have G100 and/or if driver cannot detect memory, you see
	     strange pattern on screen and so on. Devices not enabled by BIOS
	     are still initialized. It is default.
init         driver initializes every device it knows about.
memtype      specifies memory type, implies 'init'. This is valid only for G200
	     and G400 and has following meaning:

	       G200:
		 -  0 -> 2x128Kx32 chips, 2MB onboard, probably sgram
		 -  1 -> 2x128Kx32 chips, 4MB onboard, probably sgram
		 -  2 -> 2x256Kx32 chips, 4MB onboard, probably sgram
		 -  3 -> 2x256Kx32 chips, 8MB onboard, probably sgram
		 -  4 -> 2x512Kx16 chips, 8/16MB onboard, probably sdram only
		 -  5 -> same as above
		 -  6 -> 4x128Kx32 chips, 4MB onboard, probably sgram
		 -  7 -> 4x128Kx32 chips, 8MB onboard, probably sgram
	       G400:
		 -  0 -> 2x512Kx16 SDRAM, 16/32MB
		 -	 2x512Kx32 SGRAM, 16/32MB
		 -  1 -> 2x256Kx32 SGRAM, 8/16MB
		 -  2 -> 4x128Kx32 SGRAM, 8/16MB
		 -  3 -> 4x512Kx32 SDRAM, 32MB
		 -  4 -> 4x256Kx32 SGRAM, 16/32MB
		 -  5 -> 2x1Mx32 SDRAM, 32MB
		 -  6 -> reserved
		 -  7 -> reserved

	     You should use sdram or sgram parameter in addition to memtype
	     parameter.
nomtrr       disables write combining on frame buffer. This slows down driver
	     but there is reported minor incompatibility between GUS DMA and
	     XFree under high loads if write combining is enabled (sound
	     dropouts).
mtrr         enables write combining on frame buffer. It speeds up video
	     accesses much. It is default. You must have MTRR support enabled
	     in kernel and your CPU must have MTRR (f.e. Pentium II have them).
sgram        tells to driver that you have Gxx0 with SGRAM memory. It has no
	     effect without `init`.
sdram        tells to driver that you have Gxx0 with SDRAM memory.
	     It is a default.
inv24        change timings parameters for 24bpp modes on Millennium and
	     Millennium II. Specify this if you see strange color shadows
	     around  characters.
noinv24      use standard timings. It is the default.
inverse      invert colors on screen (for LCD displays)
noinverse    show true colors on screen. It is default.
dev:X        bind driver to device X. Driver numbers device from 0 up to N,
	     where device 0 is first `known` device found, 1 second and so on.
	     lspci lists devices in this order.
	     Default is `every` known device.
nohwcursor   disables hardware cursor (use software cursor instead).
hwcursor     enables hardware cursor. It is default. If you are using
	     non-accelerated mode (`noaccel` or `fbset -accel false`), software
	     cursor is used (except for text mode).
noblink      disables cursor blinking. Cursor in text mode always blinks (hw
	     limitation).
blink        enables cursor blinking. It is default.
nofastfont   disables fastfont feature. It is default.
fastfont:X   enables fastfont feature. X specifies size of memory reserved for
	     font data, it must be >= (fontwidth*fontheight*chars_in_font)/8.
	     It is faster on Gx00 series, but slower on older cards.
grayscale    enable grayscale summing. It works in PSEUDOCOLOR modes (text,
	     4bpp, 8bpp). In DIRECTCOLOR modes it is limited to characters
	     displayed through putc/putcs. Direct accesses to framebuffer
	     can paint colors.
nograyscale  disable grayscale summing. It is default.
cross4MB     enables that pixel line can cross 4MB boundary. It is default for
	     non-Millennium.
nocross4MB   pixel line must not cross 4MB boundary. It is default for
	     Millennium I or II, because of these devices have hardware
	     limitations which do not allow this. But this option is
	     incompatible with some (if not all yet released) versions of
	     XF86_FBDev.
dfp          enables digital flat panel interface. This option is incompatible
	     with secondary (TV) output - if DFP is active, TV output must be
	     inactive and vice versa. DFP always uses same timing as primary
	     (monitor) output.
dfp:X        use settings X for digital flat panel interface. X is number from
	     0 to 0xFF, and meaning of each individual bit is described in
	     G400 manual, in description of DAC register 0x1F. For normal
	     operation you should set all bits to zero, except lowest bit. This
	     lowest bit selects who is source of display clocks, whether G400,
	     or panel. Default value is now read back from hardware - so you
	     should specify this value only if you are also using `init`
	     parameter.
outputs:XYZ  set mapping between CRTC and outputs. Each letter can have value
	     of 0 (for no CRTC), 1 (CRTC1) or 2 (CRTC2), and first letter
	     corresponds to primary analog output, second letter to the
	     secondary analog output and third letter to the DVI output.
	     Default setting is 100 for cards below G400 or G400 without DFP,
	     101 for G400 with DFP, and 111 for G450 and G550. You can set
	     mapping only on first card, use matroxset for setting up other
	     devices.
vesa:X       selects startup videomode. X is number from 0 to 0x1FF, see table
	     above for detailed explanation. Default is 640x480x8bpp if driver
	     has 8bpp support. Otherwise first available of 640x350x4bpp,
	     640x480x15bpp, 640x480x24bpp, 640x480x32bpp or 80x25 text
	     (80x25 text is always available).
============ ===================================================================

If you are not satisfied with videomode selected by `vesa` option, you
can modify it with these options:

============ ===================================================================
xres:X       horizontal resolution, in pixels. Default is derived from `vesa`
	     option.
yres:X       vertical resolution, in pixel lines. Default is derived from `vesa`
	     option.
upper:X      top boundary: lines between end of VSYNC pulse and start of first
	     pixel line of picture. Default is derived from `vesa` option.
lower:X      bottom boundary: lines between end of picture and start of VSYNC
	     pulse. Default is derived from `vesa` option.
vslen:X      length of VSYNC pulse, in lines. Default is derived from `vesa`
	     option.
left:X       left boundary: pixels between end of HSYNC pulse and first pixel.
	     Default is derived from `vesa` option.
right:X      right boundary: pixels between end of picture and start of HSYNC
	     pulse. Default is derived from `vesa` option.
hslen:X      length of HSYNC pulse, in pixels. Default is derived from `vesa`
	     option.
pixclock:X   dotclocks, in ps (picoseconds). Default is derived from `vesa`
	     option and from `fh` and `fv` options.
sync:X       sync. pulse - bit 0 inverts HSYNC polarity, bit 1 VSYNC polarity.
	     If bit 3 (value 0x08) is set, composite sync instead of HSYNC is
	     generated. If bit 5 (value 0x20) is set, sync on green is turned
	     on. Do not forget that if you want sync on green, you also probably
	     want composite sync.
	     Default depends on `vesa`.
depth:X      Bits per pixel: 0=text, 4,8,15,16,24 or 32. Default depends on
	     `vesa`.
============ ===================================================================

If you know capabilities of your monitor, you can specify some (or all) of
`maxclk`, `fh` and `fv`. In this case, `pixclock` is computed so that
pixclock <= maxclk, real_fh <= fh and real_fv <= fv.

============ ==================================================================
maxclk:X     maximum dotclock. X can be specified in MHz, kHz or Hz. Default is
	     `don`t care`.
fh:X         maximum horizontal synchronization frequency. X can be specified
	     in kHz or Hz. Default is `don't care`.
fv:X         maximum vertical frequency. X must be specified in Hz. Default is
	     70 for modes derived from `vesa` with yres <= 400, 60Hz for
	     yres > 400.
============ ==================================================================


Limitations
===========

There are known and unknown bugs, features and misfeatures.
Currently there are following known bugs:

 - SVGALib does not restore screen on exit
 - generic fbcon-cfbX procedures do not work on Alphas. Due to this,
   `noaccel` (and cfb4 accel) driver does not work on Alpha. So everyone
   with access to `/dev/fb*` on Alpha can hang machine (you should restrict
   access to `/dev/fb*` - everyone with access to this device can destroy
   your monitor, believe me...).
 - 24bpp does not support correctly XF-FBDev on big-endian architectures.
 - interlaced text mode is not supported; it looks like hardware limitation,
   but I'm not sure.
 - Gxx0 SGRAM/SDRAM is not autodetected.
 - maybe more...

And following misfeatures:

 - SVGALib does not restore screen on exit.
 - pixclock for text modes is limited by hardware to

    - 83 MHz on G200
    - 66 MHz on Millennium I
    - 60 MHz on Millennium II

   Because I have no access to other devices, I do not know specific
   frequencies for them. So driver does not check this and allows you to
   set frequency higher that this. It causes sparks, black holes and other
   pretty effects on screen. Device was not destroyed during tests. :-)
 - my Millennium G200 oscillator has frequency range from 35 MHz to 380 MHz
   (and it works with 8bpp on about 320 MHz dotclocks (and changed mclk)).
   But Matrox says on product sheet that VCO limit is 50-250 MHz, so I believe
   them (maybe that chip overheats, but it has a very big cooler (G100 has
   none), so it should work).
 - special mixed video/graphics videomodes of Mystique and Gx00 - 2G8V16 and
   G16V16 are not supported
 - color keying is not supported
 - feature connector of Mystique and Gx00 is set to VGA mode (it is disabled
   by BIOS)
 - DDC (monitor detection) is supported through dualhead driver
 - some check for input values are not so strict how it should be (you can
   specify vslen=4000 and so on).
 - maybe more...

And following features:

 - 4bpp is available only on Millennium I and Millennium II. It is hardware
   limitation.
 - selection between 1:5:5:5 and 5:6:5 16bpp videomode is done by -rgba
   option of fbset: "fbset -depth 16 -rgba 5,5,5" selects 1:5:5:5, anything
   else selects 5:6:5 mode.
 - text mode uses 6 bit VGA palette instead of 8 bit (one of 262144 colors
   instead of one of 16M colors). It is due to hardware limitation of
   Millennium I/II and SVGALib compatibility.


Benchmarks
==========
It is time to redraw whole screen 1000 times in 1024x768, 60Hz. It is
time for draw 6144000 characters on screen through /dev/vcsa
(for 32bpp it is about 3GB of data (exactly 3000 MB); for 8x16 font in
16 seconds, i.e. 187 MBps).
Times were obtained from one older version of driver, now they are about 3%
faster, it is kernel-space only time on P-II/350 MHz, Millennium I in 33 MHz
PCI slot, G200 in AGP 2x slot. I did not test vgacon::

  NOACCEL
	8x16                 12x22
	Millennium I  G200   Millennium I  G200
  8bpp    16.42         9.54   12.33         9.13
  16bpp   21.00        15.70   19.11        15.02
  24bpp   36.66        36.66   35.00        35.00
  32bpp   35.00        30.00   33.85        28.66

  ACCEL, nofastfont
	8x16                 12x22                6x11
	Millennium I  G200   Millennium I  G200   Millennium I  G200
  8bpp     7.79         7.24   13.55         7.78   30.00        21.01
  16bpp    9.13         7.78   16.16         7.78   30.00        21.01
  24bpp   14.17        10.72   18.69        10.24   34.99        21.01
  32bpp   16.15	     16.16   18.73        13.09   34.99        21.01

  ACCEL, fastfont
	8x16                 12x22                6x11
	Millennium I  G200   Millennium I  G200   Millennium I  G200
  8bpp     8.41         6.01    6.54         4.37   16.00        10.51
  16bpp    9.54         9.12    8.76         6.17   17.52        14.01
  24bpp   15.00        12.36   11.67        10.00   22.01        18.32
  32bpp   16.18        18.29*  12.71        12.74   24.44        21.00

  TEXT
	8x16
	Millennium I  G200
  TEXT     3.29         1.50

  * Yes, it is slower than Millennium I.


Dualhead G400
=============
Driver supports dualhead G400 with some limitations:
 + secondary head shares videomemory with primary head. It is not problem
   if you have 32MB of videoram, but if you have only 16MB, you may have
   to think twice before choosing videomode (for example twice 1880x1440x32bpp
   is not possible).
 + due to hardware limitation, secondary head can use only 16 and 32bpp
   videomodes.
 + secondary head is not accelerated. There were bad problems with accelerated
   XFree when secondary head used to use acceleration.
 + secondary head always powerups in 640x480@60-32 videomode. You have to use
   fbset to change this mode.
 + secondary head always powerups in monitor mode. You have to use fbmatroxset
   to change it to TV mode. Also, you must select at least 525 lines for
   NTSC output and 625 lines for PAL output.
 + kernel is not fully multihead ready. So some things are impossible to do.
 + if you compiled it as module, you must insert i2c-matroxfb, matroxfb_maven
   and matroxfb_crtc2 into kernel.


Dualhead G450
=============
Driver supports dualhead G450 with some limitations:
 + secondary head shares videomemory with primary head. It is not problem
   if you have 32MB of videoram, but if you have only 16MB, you may have
   to think twice before choosing videomode.
 + due to hardware limitation, secondary head can use only 16 and 32bpp
   videomodes.
 + secondary head is not accelerated.
 + secondary head always powerups in 640x480@60-32 videomode. You have to use
   fbset to change this mode.
 + TV output is not supported
 + kernel is not fully multihead ready, so some things are impossible to do.
 + if you compiled it as module, you must insert matroxfb_g450 and matroxfb_crtc2
   into kernel.

Petr Vandrovec <vandrove@vc.cvut.cz>