[U-Boot] AMCC 405EX Trap

[Stefan Roese <sr@denx.de>]

On Monday 04 May 2009, Jonathan Haws wrote:
> > From my experience you can't be sure that SDRAM setting are "currect" at
> > this
> > stage.
>
> Would that be the case on our other 6 boards then?  We have 6 boards that
> are up and running with the exact same U-Boot binary file.  If there was a
> problem with the SDRAM settings on one board, would not the other board
> show the same symptoms?

Not necessarily. Some SDRAM related problems only show very seldom or only 
under specific conditions (temperature and/or component differences etc). 
This "might" explain why some boards show no problems and other do.

> That is the reason why I have not dug deeper into 
> the SDRAM initialization.  However, I will take your advice and do so,
> because if there is a problem there, then the other boards may be
> experiencing problems, just not to the extent that this one is.
>
> > > and that I am using the right addresses and chip
> > > selects for the data cache.
> > >
> > > Currently I am leaning toward an SDRAM problem because I get about a 20
> > > second pause when U-Boot tries to relocate to RAM.
> >
> > Yes, I'm pretty sure that you have some SDRAM related problems. Either
> > configuration is non-optimal, or even (perhaps more unlikely) a hardware
> > problem. I suggest that you re-check the DDR2 autocalibration (method A &
> > B).
>
> Thanks for confirming my initial hunch - problem lies in SDRAM.  I will let
> you know what I find - whether it is a hardware or software problem.
>
> One thing I may mention is that we had the SDRAM chips re-balled before
> they were mounted on the board.  Maybe something went wrong during that
> process on these chips on the problem board - who knows.

I see. This could be a problem.

I suggest that you run some stress tests in a conditioning cabinet to see if 
the other boards don't show any problems.

Best regards,
Stefan

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