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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
11 The 'video-mode' environment variable can be used to enable and configure
12 some video drivers. The format matches the video= command-line option used
13 for 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
25 U-Boot MPC8xx video controller driver
26 =====================================
27
28 The driver has been tested with the following configurations:
29
30 - MPC823FADS with AD7176 on a PAL TV (YCbYCr) - arsenio@tin.it
31
32 Example: video-mode=fslfb:1280x1024-32@60,monitor=dvi
33
34
35 U-Boot sunxi video controller driver
36 ====================================
37
38 U-Boot supports hdmi and lcd output on Allwinner sunxi SoCs, lcd output
39 requires the CONFIG_VIDEO_LCD_MODE Kconfig value to be set.
40
41 The 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
76 For example to always use the hdmi connector, even if no cable is inserted,
77 using edid info when available and otherwise initalizing it at 1024x768@60Hz,
78 use: "setenv video-mode sunxi:1024x768-24@60,monitor=dvi,hpd=0,edid=1".