| 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". | |
| TrueType fonts | |
| -------------- | |
| U-Boot supports the use of antialiased TrueType fonts on some platforms. This | |
| has been tested in x86, ARMv7 and sandbox. | |
| To enable this, select CONFIG_CONSOLE_TRUETYPE. You can choose between several | |
| fonts, with CONSOLE_TRUETYPE_NIMBUS being the default. | |
| TrueType support requires floating point at present. On ARMv7 platforms you | |
| need to disable use of the private libgcc. You can do this by disabling | |
| CONFIG_USE_PRIVATE_LIBGCC. See chromebook_jerry for an example. Note that this | |
| increases U-Boot's size by about 70KB at present. | |
| On ARM you should also make sure your toolchain supports hardfp. This is | |
| normally given in the name of your toolchain, e.g. arm-linux-gnueabihf (hf | |
| means hardware floating point). You can also run gcc with -v to see if it has | |
| this option. |