[coreboot-gerrit] Change in coreboot[master]: nb/intel/x4x/raminit: Rework receive enable calibration

[Arthur Heymans (Code Review)]

Hello Paul Menzel, build bot (Jenkins), coreboot org, Nico Huber,

I'd like you to reexamine a change.  Please visit

    https://review.coreboot.org/18692

to look at the new patch set (#21).

Change subject: nb/intel/x4x/raminit: Rework receive enable calibration
......................................................................

nb/intel/x4x/raminit: Rework receive enable calibration

Moves receive enable calibration to a separate file to lighten
raminit.c a bit.

Receive enable calibration is quite similar to gm45 so it reuses some
of its function names.

The functional changes are:
* start at coarse at CAS + 1 instead of CAS - 1. Other Intel
  northbridges do this too and register dumps from vendor bios further
  support this;
* the minimum coarse is now reset for each channel;
* on the second fine search for DQS high, TAP overflow is handled by
  increasing medium;
* some settings that are not close to edges are noisy. To improve the
  results, multiple samples are taken and the next finer settings is
  also tested for consistency of the result;
* Use a struct for settings, which could be used to simplify the code
  that restores these settings on S3 resume or hot reset.

This change might improve stability.

Change-Id: I0c970455e609d3ce96a262cbf110336a2079da4d
Signed-off-by: Arthur Heymans <arthur at aheymans.xyz>
---
M src/northbridge/intel/x4x/Makefile.inc
M src/northbridge/intel/x4x/raminit_ddr2.c
A src/northbridge/intel/x4x/rcven.c
M src/northbridge/intel/x4x/x4x.h
4 files changed, 397 insertions(+), 282 deletions(-)


  git pull ssh://review.coreboot.org:29418/coreboot refs/changes/92/18692/21
-- 
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I0c970455e609d3ce96a262cbf110336a2079da4d
Gerrit-PatchSet: 21
Gerrit-Project: coreboot
Gerrit-Branch: master
Gerrit-Owner: Arthur Heymans <arthur at aheymans.xyz>
Gerrit-Reviewer: Arthur Heymans <arthur at aheymans.xyz>
Gerrit-Reviewer: Damien Zammit <damien at zamaudio.com>
Gerrit-Reviewer: Nico Huber <nico.h at gmx.de>
Gerrit-Reviewer: Patrick Rudolph <siro at das-labor.org>
Gerrit-Reviewer: Paul Menzel <paulepanter at users.sourceforge.net>
Gerrit-Reviewer: Philippe Mathieu-Daudé <philippe.mathieu.daude at gmail.com>
Gerrit-Reviewer: build bot (Jenkins) <no-reply at coreboot.org>
Gerrit-Reviewer: coreboot org <coreboot.org at gmail.com>