On Thursday 23 October 2008, Ayman M. El-Khashab wrote:
On Wed, Oct 22, 2008 at 07:12:30AM +0200, Stefan Roese wrote:
Yes, there have been issues with the "old" autocalibration code on some boards. That's one reason that AMCC provided a new version just a few weeks ago:
Thanks Stefan, I've got the hardware mostly working now.
Great, congrats.
The new calibration code did work once I got past another issue. I'll try to describe it here b/c It *might* be a bug, but I wasn't 100% sure.
First, I am using registered ecc dimms which appears to be handled in cpu/ppc4xx/44x_spd_ddr2.c
I personally have never used a registered DIMM on the 4xx systems. And I don't know of any systems that do. So it could be that this is still untested and buggy.
However, what I found by observing the registers with the abatron was that the SDRAM_MCOPT1_RDEN was not set for the registered DIMM. Following the code, it looks like it should have been set if "registered" was set, but it does not appear that it worked correctly. So of course we were off by 1/2. I forced the bit in the mcopt1 variable and that fixed all the problems.
Good.
Any thoughts or is there something I can try/contribute?
Best would be if you could provide a proper patch to fix this problem. Please see here:
http://www.denx.de/wiki/view/U-Boot/Patches
how this is done correctly.
Best regards, Stefan
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