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020fa32dc3
U-Boot supports using TrueType fonts on the console, which is useful for presenting a nice UI to users, e.g. for system recovery. Add information about how to compile this on ARM platforms, since this is not obvious. Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
98 lines
3.8 KiB
Plaintext
98 lines
3.8 KiB
Plaintext
SPDX-License-Identifier: GPL-2.0+
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/*
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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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"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|vga|composite-*] - 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 video output over the VGA connector.
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composite-pal/composite-ntsc/composite-pal-m/composite-pal-nc:
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Selects composite video output, note the specified resolution is
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ignored with composite video output.
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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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- overscan_x/overscan_y=<int> - Set x/y overscan value
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This configures a black border on the left and right resp. top and bottom
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to deal with overscanning displays. Defaults to overscan_x=32 and
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overscan_y=20 for composite monitors, 0 for other monitors.
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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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TrueType fonts
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--------------
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U-Boot supports the use of antialiased TrueType fonts on some platforms. This
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has been tested in x86, ARMv7 and sandbox.
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To enable this, select CONFIG_CONSOLE_TRUETYPE. You can choose between several
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fonts, with CONSOLE_TRUETYPE_NIMBUS being the default.
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TrueType support requires floating point at present. On ARMv7 platforms you
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need to disable use of the private libgcc. You can do this by disabling
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CONFIG_USE_PRIVATE_LIBGCC. See chromebook_jerry for an example. Note that this
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increases U-Boot's size by about 70KB at present.
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On ARM you should also make sure your toolchain supports hardfp. This is
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normally given in the name of your toolchain, e.g. arm-linux-gnueabihf (hf
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means hardware floating point). You can also run gcc with -v to see if it has
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this option.
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