[U-Boot-Users] Board boots - minor memory controller operation understanding problem

Peter Asemann peter.asemann at web.de
Sat Jun 4 18:15:02 CEST 2005

> The question is not how they work in general, but how BR0 /  OR0  are
> acting  after  a  reset  until  they  first get written to. [Which is
> problaby what your  BDM4GDB  init  script  does,  which  in  turn  is
> probably why you don't see the things you expect.]

You "misunderestimate" me. I've of course a minimal init script that 
does nothing but disable the watchdog reset. I've also already found out 
that the address put on the address bus (0xfff00100) is not influenced 
by the memory controller, that the flash is visible multiple times in 
the address space is only due to the fact that the most significant 8 
bit of the address are not connected with the flash chips.

Whatever, with your rather cryptic hint you're probable referring to the 
MPC manual subsubsection "Boot Chip-Select Operation", which states that 
upon reset. "CS0 ist asserted for every address, unless an internal 
register is accessed." Single sentences are hard to find in 1.5K pages 
manuals, btw..

So this most probably means the memory controller doesn't care the least 
bit for the address mask in OR0 before OR0 is re-written, as CS0 is 
asserted anyway, no matter what OR0[AM] is.

It'd be a lie if I alleged I had been very happy with your hint, but 
with hindsight: Thanks again.

Best regards,

Peter Asemann

More information about the U-Boot mailing list