On 13:06 Fri 31 Oct , Stefan Roese wrote: > Hi Wolfgang, > > On Friday 31 October 2008, Wolfgang Denk wrote: > > > > It is my understanding that a rework of this code is under way which > > > > will avoid the long delay for the standard boot sequence (and only > > > > need it for board bringup or intentional recalibration). > > > > > > Are you talking about storing the optimized autocalibration values in > > > FLASH, as discussed on IRC some time ago? I don't know if somebody is > > > working on > > > > Yes. I see this as a mandatory requirement. The additional delays are > > not aceptable. > > I just want to raise some concerns about this approach on boards with DIMM > modules. Here it will be hard to determine if a new DIMM module is installed. > Even a module from the same manufacturer and type (size, width etc, all the > same) will need a new autocalibration. This is probably hard to detect. > > Just my $0.02. As discuss on IRC with Stefan
we can use the EEPROM present on the DIMM to identify two Modules as point to this link as example http://www.micron.com/products/spddetail.aspx?part=MT16HTF12864HY-667F1 we have the following interested informations stored Byte Byte Description Number 64-71 MANUFACTURERS JEDEC ID CODE 73-90 MODULE PART NUMBER 95-98 MODULE SERIAL NUMBER we can check this 3 fields to be sure if it's a new modules is installed and so re-do the calibration Why the 3 fields? By experience I've seen 2 Manufacturs use the same Serial Number for 2 differents product and I've also seen a Manufactur using the same Serial Number for 2 differents Part number Best Regards, J. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
