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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