Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) ===============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) What is vesafb?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3) ===============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5) This is a generic driver for a graphic framebuffer on intel boxes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) The idea is simple:  Turn on graphics mode at boot time with the help
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) of the BIOS, and use this as framebuffer device /dev/fb0, like the m68k
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) (and other) ports do.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) This means we decide at boot time whenever we want to run in text or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) graphics mode.  Switching mode later on (in protected mode) is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) impossible; BIOS calls work in real mode only.  VESA BIOS Extensions
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) Version 2.0 are required, because we need a linear frame buffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) Advantages:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18)  * It provides a nice large console (128 cols + 48 lines with 1024x768)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19)    without using tiny, unreadable fonts.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20)  * You can run XF68_FBDev on top of /dev/fb0 (=> non-accelerated X11
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21)    support for every VBE 2.0 compliant graphics board).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22)  * Most important: boot logo :-)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) Disadvantages:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26)  * graphic mode is slower than text mode...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) How to use it?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) ==============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) Switching modes is done using the vga=... boot parameter.  Read
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) Documentation/admin-guide/svga.rst for details.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) You should compile in both vgacon (for text mode) and vesafb (for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) graphics mode). Which of them takes over the console depends on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) whenever the specified mode is text or graphics.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) The graphic modes are NOT in the list which you get if you boot with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) vga=ask and hit return. The mode you wish to use is derived from the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) VESA mode number. Here are those VESA mode numbers:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) ====== =======  =======  ======== =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) colors 640x480  800x600  1024x768 1280x1024
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) ====== =======  =======  ======== =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) 256    0x101    0x103    0x105    0x107
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 32k    0x110    0x113    0x116    0x119
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) 64k    0x111    0x114    0x117    0x11A
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) 16M    0x112    0x115    0x118    0x11B
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) ====== =======  =======  ======== =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) The video mode number of the Linux kernel is the VESA mode number plus
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) 0x200:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56)  Linux_kernel_mode_number = VESA_mode_number + 0x200
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) So the table for the Kernel mode numbers are:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) ====== =======  =======  ======== =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) colors 640x480  800x600  1024x768 1280x1024
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) ====== =======  =======  ======== =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 256    0x301    0x303    0x305    0x307
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 32k    0x310    0x313    0x316    0x319
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 64k    0x311    0x314    0x317    0x31A
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 16M    0x312    0x315    0x318    0x31B
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) ====== =======  =======  ======== =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) To enable one of those modes you have to specify "vga=ask" in the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) lilo.conf file and rerun LILO. Then you can type in the desired
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) mode at the "vga=ask" prompt. For example if you like to use
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 1024x768x256 colors you have to say "305" at this prompt.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) If this does not work, this might be because your BIOS does not support
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) linear framebuffers or because it does not support this mode at all.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) Even if your board does, it might be the BIOS which does not.  VESA BIOS
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) Extensions v2.0 are required, 1.2 is NOT sufficient.  You will get a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) "bad mode number" message if something goes wrong.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 1. Note: LILO cannot handle hex, for booting directly with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81)    "vga=mode-number" you have to transform the numbers to decimal.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 2. Note: Some newer versions of LILO appear to work with those hex values,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83)    if you set the 0x in front of the numbers.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) X11
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) ===
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) XF68_FBDev should work just fine, but it is non-accelerated.  Running
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) another (accelerated) X-Server like XF86_SVGA might or might not work.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) It depends on X-Server and graphics board.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) The X-Server must restore the video mode correctly, else you end up
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) with a broken console (and vesafb cannot do anything about this).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) Refresh rates
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) =============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) There is no way to change the vesafb video mode and/or timings after
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) booting linux.  If you are not happy with the 60 Hz refresh rate, you
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) have these options:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103)  * configure and load the DOS-Tools for the graphics board (if
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104)    available) and boot linux with loadlin.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105)  * use a native driver (matroxfb/atyfb) instead if vesafb.  If none
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106)    is available, write a new one!
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107)  * VBE 3.0 might work too.  I have neither a gfx board with VBE 3.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108)    support nor the specs, so I have not checked this yet.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) Configuration
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) =============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) The VESA BIOS provides protected mode interface for changing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) some parameters.  vesafb can use it for palette changes and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) to pan the display.  It is turned off by default because it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) seems not to work with some BIOS versions, but there are options
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) to turn it on.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) You can pass options to vesafb using "video=vesafb:option" on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) the kernel command line.  Multiple options should be separated
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) by comma, like this: "video=vesafb:ypan,inverse"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) Accepted options:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) inverse	use inverse color map
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) ========= ======================================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) ypan	  enable display panning using the VESA protected mode
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130)           interface.  The visible screen is just a window of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131)           video memory, console scrolling is done by changing the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132)           start of the window.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134)           pro:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136)                 * scrolling (fullscreen) is fast, because there is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 		  no need to copy around data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139)           kontra:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 		* scrolling only parts of the screen causes some
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 		  ugly flicker effects (boot logo flickers for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 		  example).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) ywrap	  Same as ypan, but assumes your gfx board can wrap-around
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146)           the video memory (i.e. starts reading from top if it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147)           reaches the end of video memory).  Faster than ypan.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) redraw	  Scroll by redrawing the affected part of the screen, this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150)           is the safe (and slow) default.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) vgapal	  Use the standard vga registers for palette changes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154)           This is the default.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) pmipal    Use the protected mode interface for palette changes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) mtrr:n	  Setup memory type range registers for the vesafb framebuffer
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158)           where n:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160)               - 0 - disabled (equivalent to nomtrr) (default)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161)               - 1 - uncachable
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162)               - 2 - write-back
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163)               - 3 - write-combining
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164)               - 4 - write-through
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166)           If you see the following in dmesg, choose the type that matches the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167)           old one. In this example, use "mtrr:2".
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) ...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) mtrr:     type mismatch for e0000000,8000000 old: write-back new:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 	  write-combining
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) ...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) nomtrr    disable mtrr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) vremap:n
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176)           Remap 'n' MiB of video RAM. If 0 or not specified, remap memory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177)           according to video mode. (2.5.66 patch/idea by Antonino Daplas
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178)           reversed to give override possibility (allocate more fb memory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179)           than the kernel would) to 2.4 by tmb@iki.fi)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) vtotal:n  If the video BIOS of your card incorrectly determines the total
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)           amount of video RAM, use this option to override the BIOS (in MiB).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) ========= ======================================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) Have fun!
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) Gerd Knorr <kraxel@goldbach.in-berlin.de>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) Minor (mostly typo) changes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) by Nico Schmoigl <schmoigl@rumms.uni-mannheim.de>