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7.1 Display configuration 35
field name type description
name string used to identify the panel
pixclock number Divisor for the pixel clock. Generally
3 for QVGA, 1 for higher resolution.
xres number Horizontal pixel count
yres number Vertical pixel count
act high number Clock polarity, 0 (default) or 1
hsync len number Horizontal sync pulse
left margin number Idle pixels before leftmost pixel
right margin number Idle pixels after rightmost pixel
vsync len number Vertical sync pulse
upper margin number Idle rows before topmost
lower margin number Idle rows after bottom
active number Active Matrix (1) or Passive (0)
crt number digital LCD(0) or Analog CRT(1)
rotation number landscape (0) or portrait(90)
Once you have collected this information, a corresponding entry must be
added to the list of panels.
u-boot-1.1.2/common/lcd_panels.c
To allow the testing of thes e settings and the use of a different display
without re-compiling, the lcdp boot loader command is available. It may
be used in one of the following ways:
command string description
lcdp Show the current lcd panel settings
lcdp ? Show the list of currently supported lcd panels
lcdp panelname Select and initialize panelname
lcdp + Add a new panel (prompts for details)
Note that the boot loader text display will not be updated properly if
the X and Y resolution don’t match the current default display. Use the
bmp commands to test the new panel configuration after using the lcdp +
command string.
As always, the source code is available. The two modules used to support
dynamic display selection are:
• common/cmd lcdpanels.c - defines U-Boot commands
• common/lcd panels.c - display initialization
7.1.1 What display is currently selected?
The lcdp command is used for a variety of purposes including querying the
currently selected display.
December 28, 2005 Revision 2.8