How to enable lvds in uboot 2009 for sabresd board?

[teddy123]

I am working on custom sabresd board and I would like to display a splash image on the lvds screen. For this, I have to configure lvds in the board file. Can anyone pls tell me how to configure lvds screen in uboot. Is lcd_enable() function has anything to do with it?

[fabio_estevam]

Please don't use such old U-boot version from 2009.

Just use the latest mainline U-boot and LVDS splash will work out of the box.

[teddy123]

But Fabio, I need to port Android on my custom sabresd board which in turn is based on the older version of u-boot only.

[igorpadykov]

Hi teddy

please also look at

" jive_internal="true

iMX6QD How to Add 24-bit LVDS Support in Android

~igor

[teddy123]

Hi Igor,

How is the value of the environment variable "splashimage" calculated?

[igorpadykov]

http://www.denx.de/wiki/DULG/UBootSplashScreen

~igor

[teddy123]

Hi Igor,

But I cant understood how do we set the value of splashimage variable, How do we arrive on it?

[igorpadykov]

Hi teddy

what do you mean by

"I cant understood how do we set the value of splashimage variable, How do we arrive on it"

?

[teddy123]

Hi Igor,

From my observation the value of splashimage variable for a SABRESD board is 0x30000000. I need to know do we arrive at this value?

[igorpadykov]

Hi teddy

splashimage is free memory space, in Uboot you can look at

TEXT_BASE - the pointer *start where the code is copied from the

boot device. This variable (in u-boot-2009.08 TEXT_BASE = 0x27800000 )

is defined in the file: ./u-boot/board/freescale/mx6q_sabresd/config.mk

~igor

[teddy123]

But Igor,

Why do we then specify the splashimage variable as 0x30000000 instead of 0x27800000?

[igorpadykov]

Hi teddy

0x30000000 is free address - so it is used for splashscreen,

0x27800000 is start address for Uboot loading

~igor

[teddy123]

Hi Igor,

I would like to know how the address available in the splashimage variable is mapped to a framebuffer so that the splash image is displayed over the lvds. Because, It seems we just copy the splash image to a free memory location(i.e. within setup_splash_image() function ) in uboot.

[igorpadykov]

Hi teddy

please create new thread for new questions

~igor

[igorpadykov]

Hi teddy

I think attached document may help

sect.5.4 Splash screen support

Best regards

igor

[teddy123]

Hi igor,

I have tried this too but am not able to view anything even the lvds backlight isn't getting enabled.

[saurabh206]

Hi,

teddy

you need update timing parameters for your panel. 

[teddy123]

Sorry Saurabh, am new to this wat do u mean by timing parameters?

[saurabh206]

Hi,

teddy

Which panel are you using?

What is a resolution?

[teddy123]

Am using eGalax panel with resolution 1024*768.

[saurabh206]

Hi,

static struct fb_videomode lvds_xga = {

     "XGA", 60, 1024, 768, 15385, 220, 40, 21, 7, 60, 10,

     FB_SYNC_EXT,

     FB_VMODE_NONINTERLACED,

     0,

};

Refer following file

uboot-imx\board\freescale\mx6q_sabresd\mx6q_sabresd.c