Certain registered DIMMs failed training due to an error likely introduced during historical rebase. Ensure that the SubMemclkRegDly bit is set according to BKDG recommendations on Family 15 processors. Change-Id: I24c95265dada9eabf4df280b6f2b4a1eb9cecaf1 Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com> Reviewed-on: https://review.coreboot.org/13148 Tested-by: build bot (Jenkins) Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com> Reviewed-by: Martin Roth <martinroth@google.com>