Hi,
I had the same problem with u-boot-1.3.4 on custom 460EX board with registered SODIMM. The SPD code in 4xx_spd_ddr2.c (program_copt1()) checks two SPD fields to decide whether DIMM is registered: DDRII DIMM type (offset 20) and SDRAM module attributes (offset 21).
In my case, the values in these fields do not match what code is looking for. See http://www.micron.com/products/spddetail.aspx?part=MT9HTF6472RHY-667F1 I had to modify the following peice in program_copt1() to make it work:
if (dimm_num == 0) { if (dimm_populated[dimm_num] == SDRAM_DDR1) /* DDR1 type */ mcopt1 |= SDRAM_MCOPT1_DDR1_TYPE; if (dimm_populated[dimm_num] == SDRAM_DDR2) /* DDR2 type */ mcopt1 |= SDRAM_MCOPT1_DDR2_TYPE; if (registered == 1) { /* DDR2 always buffered */ /* TODO: what about above comments ? */ mcopt1 |= SDRAM_MCOPT1_RDEN; buf0 = TRUE; } else { /* TODO: the mask 0x02 doesn't match Samsung def for byte 21. */ if ((attribute & 0x02) == 0x00) { /* buffered not supported */ buf0 = FALSE; } else { mcopt1 |= SDRAM_MCOPT1_RDEN; buf0 = TRUE; } } }
I've changed
if ((attribute & 0x02) == 0x00)
to be
if (((attribute & 0x02) == 0x00) && (attribute != 0x04))
I'm not sure this is generic enough to go into mainline, but if yes, I can try to submit a patch.
Felix.
Stefan Roese wrote:
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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