u-boot/doc/README.video
Tom Rini 83d290c56f SPDX: Convert all of our single license tags to Linux Kernel style
When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>
2018-05-07 09:34:12 -04:00

77 lines
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SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2000
* Paolo Scaffardi, AIRVENT SAM s.p.a - RIMINI(ITALY), arsenio@tin.it
*/
"video-mode" environment variable
=================================
The 'video-mode' environment variable can be used to enable and configure
some video drivers. The format matches the video= command-line option used
for Linux:
video-mode=<driver>:<xres>x<yres>-<depth>@<freq><,option=string>
<driver> The video driver name, ignored by U-Boot
<xres> The X resolution (in pixels) to use.
<yres> The Y resolution (in pixels) to use.
<depth> The color depth (in bits) to use.
<freq> The frequency (in Hz) to use.
<options> A comma-separated list of device-specific options
U-Boot MPC8xx video controller driver
=====================================
The driver has been tested with the following configurations:
- MPC823FADS with AD7176 on a PAL TV (YCbYCr) - arsenio@tin.it
Example: video-mode=fslfb:1280x1024-32@60,monitor=dvi
U-Boot sunxi video controller driver
====================================
U-Boot supports hdmi and lcd output on Allwinner sunxi SoCs, lcd output
requires the CONFIG_VIDEO_LCD_MODE Kconfig value to be set.
The sunxi U-Boot driver supports the following video-mode options:
- monitor=[none|dvi|hdmi|lcd|vga|composite-*] - Select the video output to use
none: Disable video output.
dvi/hdmi: Selects output over the hdmi connector with dvi resp. hdmi output
format, if edid is used the format is automatically selected.
lcd: Selects video output to a LCD screen.
vga: Selects video output over the VGA connector.
composite-pal/composite-ntsc/composite-pal-m/composite-pal-nc:
Selects composite video output, note the specified resolution is
ignored with composite video output.
Defaults to monitor=dvi.
- hpd=[0|1] - Enable use of the hdmi HotPlug Detect feature
0: Disabled. Configure dvi/hdmi output even if no cable is detected
1: Enabled. Fallback to the lcd / vga / none in that order (if available)
Defaults to hpd=1.
- hpd_delay=<int> - How long to wait for the hdmi HPD signal in milliseconds
When the monitor and the board power up at the same time, it may take some
time for the monitor to assert the HPD signal. This configures how long to
wait for the HPD signal before assuming no cable is connected.
Defaults to hpd_delay=500.
- edid=[0|1] - Enable use of DDC + EDID to get monitor info
0: Disabled.
1: Enabled. If valid EDID info was read from the monitor the EDID info will
overrides the xres, yres and refresh from the video-mode env. variable.
Defaults to edid=1.
- overscan_x/overscan_y=<int> - Set x/y overscan value
This configures a black border on the left and right resp. top and bottom
to deal with overscanning displays. Defaults to overscan_x=32 and
overscan_y=20 for composite monitors, 0 for other monitors.
For example to always use the hdmi connector, even if no cable is inserted,
using edid info when available and otherwise initalizing it at 1024x768@60Hz,
use: "setenv video-mode sunxi:1024x768-24@60,monitor=dvi,hpd=0,edid=1".