[U-Boot] AMCC 405EX Trap

[Jerry Van Baren <gerald.vanbaren@ge.com>]

Jonathan Haws wrote:
>> On Thursday 30 April 2009, Jonathan Haws wrote:
>>> I am certain that it is a hardware failure that is causing the machine
>>> check because I can use the exact same binary on another (identical)
>> board
>>> and have it boot just fine.  That tells me that all the EBC and SDRAM
>>> settings are correct;
>> 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?  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.
> 
> Anyway, once I get this resolved I will post the solution.
> 
> Thanks all!
> 
> Jonathan

1) Six boards work, one board fails.
2) SDRAM chips re-balled on the failing board.
3) SDRAM failing.

That sounds like a hardware/assembly problem to me.  My bet is a solder 
problem.  Have you (can you) x-ray the chips and verify the SDRAM 
soldering is OK?

Best regards,
gvb