SDRAM failures on MPC5200B

[Rafal Jaworowski]

lokowich wrote:
> We're working on bringing up a MPC5200B version of our original MPC5200 
> board using U-Boot 1.1.4 configured for Icecube/Lite5200B.  Other than 
> the CPU, the board is identical.  The bootloader crashes just after 
> relocation to RAM, often with a Program Check Exception, typically a 
> memory corruption issue.  I noticed failures at different stages after 
> relocation based on content, suggesting problems with upper SDRAM.  If I 
> force the initram to 1/2 the determined size (64MB instead of 128MB), 
> then everything works well through kernel load and initialization.  
> We've added termination resistors to improve AD signals, to no avail.  
> Memory tests work fine too.  Any help is appreciated.
> 

Assuming your RAM chips are fine, are you setting the SDelay register 
(MBAR + 0x0190)? If not, this can lead to a strange hangs similar to the 
described. For details please see the current U-Boot's initdram() for 
icecube, and AN3221.

Rafal