search

open-power / hostboot

System initialization firmware for Power systems
Apache License 2.0
75 stars 97 forks source link

RCD Control Word Fix for DDR4 Dual Drop Systems #103

Open hrpreetham opened 7 years ago

hrpreetham commented 7 years ago

The MSI and Suzho, we came across a common problem where the common settings used to fail calibration at istep as the RCD word was not getting set properly.

The root cause was fixed and this issue is to keep track to merge the Fix.

The issue was with the way we were sending out the RCD control words in draminit. As mentioned, this code path had never been run through (ddr4 2R dual drop) .. in DDR4 CS0 needs to be pulled low on each dimm meaning CS0 for dimm 0 and CS4 for dimm 1. The code in dev and HB has CS0 being pulled twice. After playing with parity error injects it became obvious something was fishy about rank 4 being impervious to fails. Given that, current fix code is in /opt/openpower/memtools/lwm_draminit_override

The mss_ddr4_funcs.C is to be updated.

dcrowell77 commented 7 years ago

@hrpreetham - Please include the specific version number of the file with the fix when you have it.