New patch to review for coreboot: nb/amd/mct_ddr3: Do not constantly reset read data timing registers to 0

[Timothy Pearson]

Timothy Pearson ([e-mail]) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/14543

-gerrit

commit edde5c3ce196e23cf565aace4d6dd68d0ac258ed
Author: Timothy Pearson 
Date:   Fri Apr 29 01:35:21 2016 -0500

nb/amd/mct_ddr3: Do not constantly reset read data timing registers to 0

During DQS receiver enable cycle training on Family 15h platforms the
    read data timing registers were inadvertently set to zero on every
    lane training attempt.

Ensure that the read data timing registers are correctly set after
    each lane is trained in receiver enable cycle training.  This allows
    more than one RDIMM to function on a given DCT channel.

Change-Id: I87d732f0383e9785a73b57e6f48855f3e872f1f9
    Tested-On: ASUS KGPE-D16
    Tested-With: 1x Opteron 6262HE
    Tested-With: 4x Crucial 36KSF1G72PZ-1G6M1 (slots A2 / A1 / B2 / B1)
    Signed-off-by: Timothy Pearson 
---
 src/northbridge/amd/amdmct/mct_ddr3/mctdqs_d.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/northbridge/amd/amdmct/mct_ddr3/mctdqs_d.c b/src/northbridge/amd/amdmct/mct_ddr3/mctdqs_d.c
index 81e22a8..7ef2900 100644
--- a/src/northbridge/amd/amdmct/mct_ddr3/mctdqs_d.c
+++ b/src/northbridge/amd/amdmct/mct_ddr3/mctdqs_d.c
@@ -1687,6 +1687,11 @@ static void TrainDQSReceiverEnCyc_D_Fam15(struct MCTStatStruc *pMCTstat,
    		/* 2.10.5.8.3 (2) */
    		read_dqs_receiver_enable_control_registers(initial_phy_phase_delay, dev, dct, dimm, index_reg);

+			/* Reset the read data timing registers to 1UI before calculating MaxRdLatency */
+			for (internal_lane = 0; internal_lane < MAX_BYTE_LANES; internal_lane++)
+				current_read_dqs_delay[internal_lane] = 0x20;
+			write_dqs_read_data_timing_registers(current_read_dqs_delay, dev, dct, dimm, index_reg);
+
    		for (lane = 0; lane < lane_count; lane++) {
    			/* Initialize variables */
    			memset(dqs_results_array, 0, sizeof(dqs_results_array));
@@ -1711,11 +1716,6 @@ static void TrainDQSReceiverEnCyc_D_Fam15(struct MCTStatStruc *pMCTstat,
    				/* 2.10.5.8.3 (4 A) */
    				write_dqs_receiver_enable_control_registers(current_phy_phase_delay, dev, dct, dimm, index_reg);

-					/* Reset the read data timing registers to 1UI before calculating MaxRdLatency */
-					for (internal_lane = 0; internal_lane < MAX_BYTE_LANES; internal_lane++)
-						current_read_dqs_delay[internal_lane] = 0x20;
-					write_dqs_read_data_timing_registers(current_read_dqs_delay, dev, dct, dimm, index_reg);
-
    				/* Calculate and program MaxRdLatency */
    				Calc_SetMaxRdLatency_D_Fam15(pMCTstat, pDCTstat, dct, 0);

@@ -1769,6 +1769,7 @@ static void TrainDQSReceiverEnCyc_D_Fam15(struct MCTStatStruc *pMCTstat,

/* Update hardware registers with final values */
    					write_dqs_receiver_enable_control_registers(current_phy_phase_delay, dev, dct, dimm, index_reg);
+						TrainDQSRdWrPos_D_Fam15(pMCTstat, pDCTstat, dct, Receiver, Receiver + 2, lane, lane + 1);
    					break;
    				}
    				prev = dqs_results_array[current_phy_phase_delay[lane]];