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https://github.com/AsahiLinux/u-boot
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7fad8a9802
In some extreme cases it may be necessary to wait 1.5 seconds or more for a hpd signal to show up (and be able to read edid info), but we do not want to penalize all headless boots with an extra second boot delay, so add a hpd_delay parameter which can be set through the video-mode env. variable. While at it raise the default from 300ms to 500ms as 300 may very well be too low in many cases. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Ian Campbell <ijc@hellion.org.uk>
70 lines
2.6 KiB
Text
70 lines
2.6 KiB
Text
/*
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* (C) Copyright 2000
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* Paolo Scaffardi, AIRVENT SAM s.p.a - RIMINI(ITALY), arsenio@tin.it
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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"video-mode" environment variable
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=================================
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The 'video-mode' environment variable can be used to enable and configure
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some video drivers. The format matches the video= command-line option used
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for Linux:
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video-mode=<driver>:<xres>x<yres>-<depth>@<freq><,option=string>
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<driver> The video driver name, ignored by U-Boot
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<xres> The X resolution (in pixels) to use.
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<yres> The Y resolution (in pixels) to use.
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<depth> The color depth (in bits) to use.
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<freq> The frequency (in Hz) to use.
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<options> A comma-separated list of device-specific options
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U-Boot MPC8xx video controller driver
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=====================================
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The driver has been tested with the following configurations:
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- MPC823FADS with AD7176 on a PAL TV (YCbYCr) - arsenio@tin.it
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Example: video-mode=fslfb:1280x1024-32@60,monitor=dvi
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U-boot sunxi video controller driver
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====================================
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U-boot supports hdmi and lcd output on Allwinner sunxi SoCs, lcd output
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requires the CONFIG_VIDEO_LCD_MODE Kconfig value to be set.
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The sunxi u-boot driver supports the following video-mode options:
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- monitor=[none|dvi|hdmi|lcd] - Select the video output to use
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none: Disable video output.
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dvi/hdmi: Selects output over the hdmi connector with dvi resp. hdmi output
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format, if edid is used the format is automatically selected.
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lcd: Selects video output to a LCD screen.
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vga: Selects bideo output over the VGA connector.
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Defaults to monitor=dvi.
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- hpd=[0|1] - Enable use of the hdmi HotPlug Detect feature
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0: Disabled. Configure dvi/hdmi output even if no cable is detected
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1: Enabled. Fallback to the lcd / vga / none in that order (if available)
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Defaults to hpd=1.
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- hpd_delay=<int> - How long to wait for the hdmi HPD signal in milliseconds
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When the monitor and the board power up at the same time, it may take some
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time for the monitor to assert the HPD signal. This configures how long to
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wait for the HPD signal before assuming no cable is connected.
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Defaults to hpd_delay=500.
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- edid=[0|1] - Enable use of DDC + EDID to get monitor info
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0: Disabled.
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1: Enabled. If valid EDID info was read from the monitor the EDID info will
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overrides the xres, yres and refresh from the video-mode env. variable.
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Defaults to edid=1.
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For example to always use the hdmi connector, even if no cable is inserted,
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using edid info when available and otherwise initalizing it at 1024x768@60Hz,
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use: "setenv video-mode sunxi:1024x768-24@60,monitor=dvi,hpd=0,edid=1".
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