1SPDX-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
7"video-mode" environment variable
8=================================
9
10The 'video-mode' environment variable can be used to enable and configure
11some video drivers.  The format matches the video= command-line option used
12for Linux:
13
14	video-mode=<driver>:<xres>x<yres>-<depth>@<freq><,option=string>
15
16	<driver>	The video driver name, ignored by U-Boot
17	<xres>		The X resolution (in pixels) to use.
18	<yres>		The Y resolution (in pixels) to use.
19	<depth>		The color depth (in bits) to use.
20	<freq>		The frequency (in Hz) to use.
21	<options>	A comma-separated list of device-specific options
22
23
24U-Boot MPC8xx video controller driver
25=====================================
26
27The driver has been tested with the following configurations:
28
29- MPC823FADS with AD7176 on a PAL TV (YCbYCr)	- arsenio@tin.it
30
31Example: video-mode=fslfb:1280x1024-32@60,monitor=dvi
32
33
34U-Boot sunxi video controller driver
35====================================
36
37U-Boot supports hdmi and lcd output on Allwinner sunxi SoCs, lcd output
38requires the CONFIG_VIDEO_LCD_MODE Kconfig value to be set.
39
40The sunxi U-Boot driver supports the following video-mode options:
41
42- monitor=[none|dvi|hdmi|lcd|vga|composite-*] - Select the video output to use
43 none:     Disable video output.
44 dvi/hdmi: Selects output over the hdmi connector with dvi resp. hdmi output
45           format, if edid is used the format is automatically selected.
46 lcd:      Selects video output to a LCD screen.
47 vga:      Selects video output over the VGA connector.
48 composite-pal/composite-ntsc/composite-pal-m/composite-pal-nc:
49           Selects composite video output, note the specified resolution is
50           ignored with composite video output.
51 Defaults to monitor=dvi.
52
53- hpd=[0|1] - Enable use of the hdmi HotPlug Detect feature
54 0: Disabled. Configure dvi/hdmi output even if no cable is detected
55 1: Enabled.  Fallback to the lcd / vga / none in that order (if available)
56 Defaults to hpd=1.
57
58- hpd_delay=<int> - How long to wait for the hdmi HPD signal in milliseconds
59 When the monitor and the board power up at the same time, it may take some
60 time for the monitor to assert the HPD signal. This configures how long to
61 wait for the HPD signal before assuming no cable is connected.
62 Defaults to hpd_delay=500.
63
64- edid=[0|1] - Enable use of DDC + EDID to get monitor info
65 0: Disabled.
66 1: Enabled. If valid EDID info was read from the monitor the EDID info will
67    overrides the xres, yres and refresh from the video-mode env. variable.
68 Defaults to edid=1.
69
70- overscan_x/overscan_y=<int> - Set x/y overscan value
71 This configures a black border on the left and right resp. top and bottom
72 to deal with overscanning displays. Defaults to overscan_x=32 and
73 overscan_y=20 for composite monitors, 0 for other monitors.
74
75For example to always use the hdmi connector, even if no cable is inserted,
76using edid info when available and otherwise initalizing it at 1024x768@60Hz,
77use: "setenv video-mode sunxi:1024x768-24@60,monitor=dvi,hpd=0,edid=1".
78
79
80TrueType fonts
81--------------
82
83U-Boot supports the use of antialiased TrueType fonts on some platforms. This
84has been tested in x86, ARMv7 and sandbox.
85
86To enable this, select CONFIG_CONSOLE_TRUETYPE. You can choose between several
87fonts, with CONSOLE_TRUETYPE_NIMBUS being the default.
88
89TrueType support requires floating point at present. On ARMv7 platforms you
90need to disable use of the private libgcc. You can do this by disabling
91CONFIG_USE_PRIVATE_LIBGCC. See chromebook_jerry for an example. Note that this
92increases U-Boot's size by about 70KB at present.
93
94On ARM you should also make sure your toolchain supports hardfp. This is
95normally given in the name of your toolchain, e.g. arm-linux-gnueabihf (hf
96means hardware floating point). You can also run gcc with -v to see if it has
97this option.
98