New patch to review for coreboot: intel raminit: fix random raminit failures

[Patrick Rudolph]

Patrick Rudolph ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/11248

-gerrit

commit bdbf1fe4cbd4ce4f9ea1e9addb649365edcde970
Author: Patrick Rudolph 
Date:   Mon Aug 17 19:24:12 2015 +0200

intel raminit: fix random raminit failures

Issue observed:
        Intel raminit works in about 50% of all test-cases on lenovo x220.

Problem solution:
        Prefer a smaller valid value over the measured one for
        initial timB timings.

Final testing result:
        Tests on x220 shows that the issue was resolved.
        The test system booted successfully ten times in a row.
        Tests on Gigabyte GA-B75M-D3H revealed no regressions.

Test system:
        * Intel Pentium CPU G2130
        * Gigabyte GA-B75M-D3H
        * DIMM: "Crucial 2GB 256Mx64 CT2566aBA160BJ"

Change-Id: I1a115a45d5febf351d89721ece79eaf43f7ee8a0
    Signed-off-by: Patrick Rudolph 
---
 src/northbridge/intel/sandybridge/raminit_native.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/northbridge/intel/sandybridge/raminit_native.c b/src/northbridge/intel/sandybridge/raminit_native.c
index 286493b..90c34cf 100644
--- a/src/northbridge/intel/sandybridge/raminit_native.c
+++ b/src/northbridge/intel/sandybridge/raminit_native.c
@@ -2266,7 +2266,17 @@ static void discover_timB(ramctr_timing * ctrl, int channel, int slotrank)
    }
    FOR_ALL_LANES {
    	struct run rn = get_longest_zero_run(statistics[lane], 128);
-		ctrl->timings[channel][slotrank].lanes[lane].timB = rn.start;
+		if (rn.start < rn.middle) {
+			ctrl->timings[channel][slotrank].lanes[lane].timB = rn.start;
+		} else {
+			/* In this case statistics[lane][7f] and statistics[lane][0] are
+			 * both zero.
+			 * Prefer a smaller value over rn.start to prevent failures in
+			 * the following write tests.
+			 */
+			ctrl->timings[channel][slotrank].lanes[lane].timB = 0;
+		}
+
    	if (rn.all)
    		die("timB discovery failed");
    	printram("Bval: %d, %d, %d, %x\n", channel, slotrank,