README.video 3.8 KB

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  1. SPDX-License-Identifier: GPL-2.0+
  2. /*
  3. * (C) Copyright 2000
  4. * Paolo Scaffardi, AIRVENT SAM s.p.a - RIMINI(ITALY), arsenio@tin.it
  5. */
  6. "video-mode" environment variable
  7. =================================
  8. The 'video-mode' environment variable can be used to enable and configure
  9. some video drivers. The format matches the video= command-line option used
  10. for Linux:
  11. video-mode=<driver>:<xres>x<yres>-<depth>@<freq><,option=string>
  12. <driver> The video driver name, ignored by U-Boot
  13. <xres> The X resolution (in pixels) to use.
  14. <yres> The Y resolution (in pixels) to use.
  15. <depth> The color depth (in bits) to use.
  16. <freq> The frequency (in Hz) to use.
  17. <options> A comma-separated list of device-specific options
  18. U-Boot MPC8xx video controller driver
  19. =====================================
  20. The driver has been tested with the following configurations:
  21. - MPC823FADS with AD7176 on a PAL TV (YCbYCr) - arsenio@tin.it
  22. Example: video-mode=fslfb:1280x1024-32@60,monitor=dvi
  23. U-Boot sunxi video controller driver
  24. ====================================
  25. U-Boot supports hdmi and lcd output on Allwinner sunxi SoCs, lcd output
  26. requires the CONFIG_VIDEO_LCD_MODE Kconfig value to be set.
  27. The sunxi U-Boot driver supports the following video-mode options:
  28. - monitor=[none|dvi|hdmi|lcd|vga|composite-*] - Select the video output to use
  29. none: Disable video output.
  30. dvi/hdmi: Selects output over the hdmi connector with dvi resp. hdmi output
  31. format, if edid is used the format is automatically selected.
  32. lcd: Selects video output to a LCD screen.
  33. vga: Selects video output over the VGA connector.
  34. composite-pal/composite-ntsc/composite-pal-m/composite-pal-nc:
  35. Selects composite video output, note the specified resolution is
  36. ignored with composite video output.
  37. Defaults to monitor=dvi.
  38. - hpd=[0|1] - Enable use of the hdmi HotPlug Detect feature
  39. 0: Disabled. Configure dvi/hdmi output even if no cable is detected
  40. 1: Enabled. Fallback to the lcd / vga / none in that order (if available)
  41. Defaults to hpd=1.
  42. - hpd_delay=<int> - How long to wait for the hdmi HPD signal in milliseconds
  43. When the monitor and the board power up at the same time, it may take some
  44. time for the monitor to assert the HPD signal. This configures how long to
  45. wait for the HPD signal before assuming no cable is connected.
  46. Defaults to hpd_delay=500.
  47. - edid=[0|1] - Enable use of DDC + EDID to get monitor info
  48. 0: Disabled.
  49. 1: Enabled. If valid EDID info was read from the monitor the EDID info will
  50. overrides the xres, yres and refresh from the video-mode env. variable.
  51. Defaults to edid=1.
  52. - overscan_x/overscan_y=<int> - Set x/y overscan value
  53. This configures a black border on the left and right resp. top and bottom
  54. to deal with overscanning displays. Defaults to overscan_x=32 and
  55. overscan_y=20 for composite monitors, 0 for other monitors.
  56. For example to always use the hdmi connector, even if no cable is inserted,
  57. using edid info when available and otherwise initalizing it at 1024x768@60Hz,
  58. use: "setenv video-mode sunxi:1024x768-24@60,monitor=dvi,hpd=0,edid=1".
  59. TrueType fonts
  60. --------------
  61. U-Boot supports the use of antialiased TrueType fonts on some platforms. This
  62. has been tested in x86, ARMv7 and sandbox.
  63. To enable this, select CONFIG_CONSOLE_TRUETYPE. You can choose between several
  64. fonts, with CONSOLE_TRUETYPE_NIMBUS being the default.
  65. TrueType support requires floating point at present. On ARMv7 platforms you
  66. need to disable use of the private libgcc. You can do this by disabling
  67. CONFIG_USE_PRIVATE_LIBGCC. See chromebook_jerry for an example. Note that this
  68. increases U-Boot's size by about 70KB at present.
  69. On ARM you should also make sure your toolchain supports hardfp. This is
  70. normally given in the name of your toolchain, e.g. arm-linux-gnueabihf (hf
  71. means hardware floating point). You can also run gcc with -v to see if it has
  72. this option.