[U-Boot-Users] A question about initialization of SDRAM

Wolfgang Denk wd at denx.de
Thu Nov 17 16:01:48 CET 2005

In message <Tx948882797899.26592 at send2.inner-21cn.com> you wrote:
> 		I am trying to use ELDK to make a u-boot on the board with MPC852T.

"the board with MPC852T"? There is many such boards, most of them differnt.

> 		There is declaration of rtx in cpu/mpc8xx/fec.c:
> 		static RTXBD *rtx = NULL;
> 		I think that "rtx" should be NULL at the first time fec_init() is entered,so the rtx will be given the value.
> 		but after the ELDK make the u-boot, "rtx" isn't NULL at the first time fec_init() is entered, it is 0xffffffff.

What makes you think so? The code is running perfectly fine  on  many
boards. Which specific problem do you see?

> 		Before the word "memctl->memc_mbmr  = 0xD0924114" in the function initdram, rtx is NULL(0x0),but after that it
> 		is 0xffffffff. Part of the fuction initdram is below:

Looks as if there was a bug in the SDRAM init sequence for your board.

> I wonder what happens in "memctl->memc_mbmr  = 0xD0924114;",would you please explain it to me ? Thanks!

Please see the processor's User's Manual; read the memory  controller

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
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