Mini2440 - LCD type as a boot parameter ?

Hi,

is it possible to specify the LCD/display type as a boot parameter ( e.g.
the 7", 3.5" or VGA-board ) ? I'm working with different LCD's and dont
want to flash a new kernel everytime i want change the display.

There is another board called Basic2440 from stkshop.com with the same
S3C2440 CPU, that should be able to switch the display mode without
recompiling. Unfortunately I can not find the kernel or drivers sources for
this specific board.
http://en.stkshop.com/Study-Dev/ARM-board-simulator/basic2440-s3c2440-ar...
-> there is a line "LCD interface: two LCD interface, use 3.5 inc LCD on
board or extern LCD, LCD-VGA-S-video can auto switch without recompile
soft."

On a Beagleboard Clone, the Devkit8000, it is possible to switch display
modes too. It goes like this:
http://www.embedinfo.com/english/support/FAQanswer.asp?id=245

thanks !

Daniel

I know there was a posting here:
http://billforums.station51.net/
about the different LCD u-boot environment variables (0tb, etc).

I assume changing the environment parameters using u-boot would allow you
to do what you want.

Dave

In kernel driver you can switch vga and display with setup proper
parameters in u-boot. E.g. mini2440=3tb means 3-display type,
t=touchscreen,b=backlight. For vga use mini2440=2. I don't have vga board
so I don't test it. Could you try?

thanks,

marek

thanks for your replies

I am still new to linux and the mini2440, so at first i have to get uboot
work. I still have the supervivi bootloader, which was preinstalled.

After that, i'll try the vga board ;)

Hi, supervivi is in NOR flash. You need to load u-boot to NAND flash.
Please don't overwrite your NOR flash otherwise you need to use JTAG ;).

marek

Hi,

yes I know, u-boot is only in NAND-flash ;)

now with u-boot installed I can select the display through the
bootargs-variable like mini2440=3tb or mini2440=4 etc, no problem with the
vga-board too , very good ^^

There is a small utility named "fw_printenv" in the uboot source tree under
tools/env. This is a program that can read or write variables in the u-boot
environment from linux-userspace. I can read the environment with
fw_printenv, but when i use fw_setenv it always corrupts the environment.
At next reboot I get a CRC Error and the environment is set to default
discarding all previous settings. This is my fw_env.config:

# MTD device name  Device offset  Env. size  Flash sector size
/dev/mtd1    0x00000    0x20000    0x20000

I'm wondering that reading the environment is possible, but writing fails.
The kernel log shows no flash oder filesystem related errors.

Thanks for help