LXR uboot/doc/README.video

   1/*
   2 * (C) Copyright 2000
   3 * Paolo Scaffardi, AIRVENT SAM s.p.a - RIMINI(ITALY), arsenio@tin.it
   4 *
   5 * SPDX-License-Identifier:     GPL-2.0+
   6 */
   7
   8"video-mode" environment variable
   9=================================
  10
  11The 'video-mode' environment variable can be used to enable and configure
  12some video drivers.  The format matches the video= command-line option used
  13for Linux:
  14
  15        video-mode=<driver>:<xres>x<yres>-<depth>@<freq><,option=string>
  16
  17        <driver>        The video driver name, ignored by U-Boot
  18        <xres>          The X resolution (in pixels) to use.
  19        <yres>          The Y resolution (in pixels) to use.
  20        <depth>         The color depth (in bits) to use.
  21        <freq>          The frequency (in Hz) to use.
  22        <options>       A comma-separated list of device-specific options
  23
  24
  25U-Boot MPC8xx video controller driver
  26=====================================
  27
  28The driver has been tested with the following configurations:
  29
  30- MPC823FADS with AD7176 on a PAL TV (YCbYCr)   - arsenio@tin.it
  31
  32Example: video-mode=fslfb:1280x1024-32@60,monitor=dvi
  33
  34
  35U-Boot sunxi video controller driver
  36====================================
  37
  38U-Boot supports hdmi and lcd output on Allwinner sunxi SoCs, lcd output
  39requires the CONFIG_VIDEO_LCD_MODE Kconfig value to be set.
  40
  41The sunxi U-Boot driver supports the following video-mode options:
  42
  43- monitor=[none|dvi|hdmi|lcd|vga|composite-*] - Select the video output to use
  44 none:     Disable video output.
  45 dvi/hdmi: Selects output over the hdmi connector with dvi resp. hdmi output
  46           format, if edid is used the format is automatically selected.
  47 lcd:      Selects video output to a LCD screen.
  48 vga:      Selects video output over the VGA connector.
  49 composite-pal/composite-ntsc/composite-pal-m/composite-pal-nc:
  50           Selects composite video output, note the specified resolution is
  51           ignored with composite video output.
  52 Defaults to monitor=dvi.
  53
  54- hpd=[0|1] - Enable use of the hdmi HotPlug Detect feature
  55 0: Disabled. Configure dvi/hdmi output even if no cable is detected
  56 1: Enabled.  Fallback to the lcd / vga / none in that order (if available)
  57 Defaults to hpd=1.
  58
  59- hpd_delay=<int> - How long to wait for the hdmi HPD signal in milliseconds
  60 When the monitor and the board power up at the same time, it may take some
  61 time for the monitor to assert the HPD signal. This configures how long to
  62 wait for the HPD signal before assuming no cable is connected.
  63 Defaults to hpd_delay=500.
  64
  65- edid=[0|1] - Enable use of DDC + EDID to get monitor info
  66 0: Disabled.
  67 1: Enabled. If valid EDID info was read from the monitor the EDID info will
  68    overrides the xres, yres and refresh from the video-mode env. variable.
  69 Defaults to edid=1.
  70
  71- overscan_x/overscan_y=<int> - Set x/y overscan value
  72 This configures a black border on the left and right resp. top and bottom
  73 to deal with overscanning displays. Defaults to overscan_x=32 and
  74 overscan_y=20 for composite monitors, 0 for other monitors.
  75
  76For example to always use the hdmi connector, even if no cable is inserted,
  77using edid info when available and otherwise initalizing it at 1024x768@60Hz,
  78use: "setenv video-mode sunxi:1024x768-24@60,monitor=dvi,hpd=0,edid=1".
  79