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authorLeah Rowe <leah@libreboot.org>2024-08-10 14:43:19 +0100
committerLeah Rowe <leah@libreboot.org>2024-08-10 14:48:01 +0100
commit877f5d6aeb6a1a62f09c95cc214c874d057310d6 (patch)
tree4a40b0d1a0ec5edb5f501087e5ed881262b896b1 /config/coreboot/haswell/patches/0017-haswell-NRI-Do-sense-amplifier-offset-training.patch
parenta15347ef1e677ca711ce706877db2416ddfd451a (diff)
coreboot/default: merge coreboot/haswell
Signed-off-by: Leah Rowe <leah@libreboot.org>
Diffstat (limited to 'config/coreboot/haswell/patches/0017-haswell-NRI-Do-sense-amplifier-offset-training.patch')
-rw-r--r--config/coreboot/haswell/patches/0017-haswell-NRI-Do-sense-amplifier-offset-training.patch476
1 files changed, 0 insertions, 476 deletions
diff --git a/config/coreboot/haswell/patches/0017-haswell-NRI-Do-sense-amplifier-offset-training.patch b/config/coreboot/haswell/patches/0017-haswell-NRI-Do-sense-amplifier-offset-training.patch
deleted file mode 100644
index 846fe9a3..00000000
--- a/config/coreboot/haswell/patches/0017-haswell-NRI-Do-sense-amplifier-offset-training.patch
+++ /dev/null
@@ -1,476 +0,0 @@
-From be58501141aa97aa544b670e566cd6cf6797c18e Mon Sep 17 00:00:00 2001
-From: Angel Pons <th3fanbus@gmail.com>
-Date: Wed, 17 Apr 2024 13:20:32 +0200
-Subject: [PATCH 17/20] haswell NRI: Do sense amplifier offset training
-
-Quoting Wikipedia:
-
- A sense amplifier is a circuit that is used to amplify and detect
- small signals in electronic systems. It is commonly used in memory
- circuits, such as dynamic random access memory (DRAM), to read and
- amplify the weak signals stored in memory cells.
-
-In this case, we're calibrating the sense amplifiers in the memory
-controller. This training procedure uses a magic "sense amp offset
-cancel" mode of the DDRIO to observe the sampled logic levels, and
-sweeps Vref to find the low-high transition for each bit lane. The
-procedure consists of two stages: the first stage centers per-byte
-Vref (to ensure per-bit Vref offsets are as small as possible) and
-the second stage centers per-bit Vref.
-
-Because this procedure uses the "sense amp offset cancel" mode, it
-does not rely on DRAM being trained. It is assumed that the memory
-controller simply makes sense amp output levels observable via the
-`DDR_DATA_TRAIN_FEEDBACK` register and that the memory bus is idle
-during this training step (so the lane voltage is Vdd / 2).
-
-Note: This procedure will need to be adapted for Broadwell because
-it has per-rank per-bit RxVref registers, whereas Haswell only has
-a single per-bit RxVref register for all ranks.
-
-Change-Id: Ia07db68763f90e9701c8a376e01279ada8dbbe07
-Signed-off-by: Angel Pons <th3fanbus@gmail.com>
----
- .../intel/haswell/native_raminit/Makefile.mk | 1 +
- .../haswell/native_raminit/raminit_main.c | 1 +
- .../haswell/native_raminit/raminit_native.h | 12 +
- .../native_raminit/train_sense_amp_offset.c | 341 ++++++++++++++++++
- .../intel/haswell/registers/mchbar.h | 2 +
- 5 files changed, 357 insertions(+)
- create mode 100644 src/northbridge/intel/haswell/native_raminit/train_sense_amp_offset.c
-
-diff --git a/src/northbridge/intel/haswell/native_raminit/Makefile.mk b/src/northbridge/intel/haswell/native_raminit/Makefile.mk
-index 8fdd17c542..4bd668a2d6 100644
---- a/src/northbridge/intel/haswell/native_raminit/Makefile.mk
-+++ b/src/northbridge/intel/haswell/native_raminit/Makefile.mk
-@@ -21,3 +21,4 @@ romstage-y += timings_refresh.c
- romstage-y += train_jedec_write_leveling.c
- romstage-y += train_read_mpr.c
- romstage-y += train_receive_enable.c
-+romstage-y += train_sense_amp_offset.c
-diff --git a/src/northbridge/intel/haswell/native_raminit/raminit_main.c b/src/northbridge/intel/haswell/native_raminit/raminit_main.c
-index 056dde1adc..ce637e2d03 100644
---- a/src/northbridge/intel/haswell/native_raminit/raminit_main.c
-+++ b/src/northbridge/intel/haswell/native_raminit/raminit_main.c
-@@ -60,6 +60,7 @@ static const struct task_entry cold_boot[] = {
- { configure_memory_map, true, "MEMMAP", },
- { do_jedec_init, true, "JEDECINIT", },
- { pre_training, true, "PRETRAIN", },
-+ { train_sense_amp_offset, true, "SOT", },
- { train_receive_enable, true, "RCVET", },
- { train_read_mpr, true, "RDMPRT", },
- { train_jedec_write_leveling, true, "JWRL", },
-diff --git a/src/northbridge/intel/haswell/native_raminit/raminit_native.h b/src/northbridge/intel/haswell/native_raminit/raminit_native.h
-index 0750904aec..95ccd0a8b3 100644
---- a/src/northbridge/intel/haswell/native_raminit/raminit_native.h
-+++ b/src/northbridge/intel/haswell/native_raminit/raminit_native.h
-@@ -22,6 +22,8 @@
- #define NUM_LANES 9
- #define NUM_LANES_NO_ECC 8
-
-+#define NUM_BITS 8
-+
- #define COMP_INT 10
-
- /* Always use 12 legs for emphasis (not trained) */
-@@ -218,6 +220,7 @@ enum raminit_status {
- RAMINIT_STATUS_MPLL_INIT_FAILURE,
- RAMINIT_STATUS_POLL_TIMEOUT,
- RAMINIT_STATUS_REUT_ERROR,
-+ RAMINIT_STATUS_SAMP_OFFSET_FAILURE,
- RAMINIT_STATUS_RCVEN_FAILURE,
- RAMINIT_STATUS_RMPR_FAILURE,
- RAMINIT_STATUS_JWRL_FAILURE,
-@@ -243,6 +246,12 @@ struct raminit_dimm_info {
- bool valid;
- };
-
-+struct vref_margin {
-+ uint8_t low;
-+ uint8_t center;
-+ uint8_t high;
-+};
-+
- struct sysinfo {
- enum raminit_boot_mode bootmode;
- enum generic_stepping stepping;
-@@ -330,6 +339,8 @@ struct sysinfo {
- uint8_t rxdqsn[NUM_CHANNELS][NUM_SLOTRANKS][NUM_LANES];
- int8_t rxvref[NUM_CHANNELS][NUM_SLOTRANKS][NUM_LANES];
-
-+ struct vref_margin rxdqvrefpb[NUM_CHANNELS][NUM_SLOTRANKS][NUM_LANES][NUM_BITS];
-+
- uint8_t clk_pi_code[NUM_CHANNELS][NUM_SLOTRANKS];
- uint8_t ctl_pi_code[NUM_CHANNELS][NUM_SLOTRANKS];
- uint8_t cke_pi_code[NUM_CHANNELS][NUM_SLOTRANKS];
-@@ -452,6 +463,7 @@ enum raminit_status convert_timings(struct sysinfo *ctrl);
- enum raminit_status configure_mc(struct sysinfo *ctrl);
- enum raminit_status configure_memory_map(struct sysinfo *ctrl);
- enum raminit_status do_jedec_init(struct sysinfo *ctrl);
-+enum raminit_status train_sense_amp_offset(struct sysinfo *ctrl);
- enum raminit_status train_receive_enable(struct sysinfo *ctrl);
- enum raminit_status train_read_mpr(struct sysinfo *ctrl);
- enum raminit_status train_jedec_write_leveling(struct sysinfo *ctrl);
-diff --git a/src/northbridge/intel/haswell/native_raminit/train_sense_amp_offset.c b/src/northbridge/intel/haswell/native_raminit/train_sense_amp_offset.c
-new file mode 100644
-index 0000000000..d4f199fefb
---- /dev/null
-+++ b/src/northbridge/intel/haswell/native_raminit/train_sense_amp_offset.c
-@@ -0,0 +1,341 @@
-+/* SPDX-License-Identifier: GPL-2.0-or-later */
-+
-+#include <assert.h>
-+#include <commonlib/bsd/clamp.h>
-+#include <console/console.h>
-+#include <delay.h>
-+#include <lib.h>
-+#include <types.h>
-+
-+#include "raminit_native.h"
-+
-+#define VREF_OFFSET_PLOT RAM_DEBUG
-+#define SAMP_OFFSET_PLOT RAM_DEBUG
-+
-+struct vref_train_data {
-+ int8_t best_sum;
-+ int8_t best_vref;
-+ int8_t sum_bits;
-+ uint8_t high_mask;
-+ uint8_t low_mask;
-+};
-+
-+static enum raminit_status train_vref_offset(struct sysinfo *ctrl)
-+{
-+ const int8_t vref_start = -15;
-+ const int8_t vref_stop = 15;
-+ const struct vref_train_data initial_vref_values = {
-+ .best_sum = -NUM_LANES,
-+ .best_vref = 0,
-+ .high_mask = 0,
-+ .low_mask = 0xff,
-+ };
-+ struct vref_train_data vref_data[NUM_CHANNELS][NUM_LANES];
-+
-+ printk(VREF_OFFSET_PLOT, "Plot of sum_bits across Vref settings\nChannel");
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ printk(VREF_OFFSET_PLOT, "\t%u\t\t", channel);
-+ }
-+
-+ printk(VREF_OFFSET_PLOT, "\nByte");
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ printk(VREF_OFFSET_PLOT, "\t");
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++) {
-+ printk(VREF_OFFSET_PLOT, "%u ", byte);
-+ vref_data[channel][byte] = initial_vref_values;
-+ union ddr_data_control_2_reg data_control_2 = {
-+ .raw = ctrl->dq_control_2[channel][byte],
-+ };
-+ data_control_2.force_bias_on = 1;
-+ data_control_2.force_rx_on = 1;
-+ mchbar_write32(DQ_CONTROL_2(channel, byte), data_control_2.raw);
-+ }
-+ }
-+
-+ /* Sweep through Vref settings and find point SampOffset of +/- 7 passes */
-+ printk(VREF_OFFSET_PLOT, "\n1/2 Vref");
-+ for (int8_t vref = vref_start; vref <= vref_stop; vref++) {
-+ printk(VREF_OFFSET_PLOT, "\n% 3d", vref);
-+
-+ /*
-+ * To perform this test, enable offset cancel mode and enable ODT.
-+ * Check results and update variables. Ideal result is all zeroes.
-+ * Clear offset cancel mode at end of test to write RX_OFFSET_VDQ.
-+ */
-+ change_1d_margin_multicast(ctrl, RdV, vref, 0, false, REG_FILE_USE_RANK);
-+
-+ /* Program settings for Vref and SampOffset = 7 (8 + 7) */
-+ mchbar_write32(DDR_DATA_RX_OFFSET_VDQ, 0xffffffff);
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ /* Propagate delay values (without a read command) */
-+ union ddr_data_control_0_reg data_control_0 = {
-+ .raw = ctrl->dq_control_0[channel],
-+ };
-+ data_control_0.read_rf_rd = 1;
-+ data_control_0.read_rf_wr = 0;
-+ data_control_0.read_rf_rank = 0;
-+ data_control_0.force_odt_on = 1;
-+ data_control_0.samp_train_mode = 1;
-+ mchbar_write32(DDR_DATA_ch_CONTROL_0(channel), data_control_0.raw);
-+ udelay(1);
-+ data_control_0.samp_train_mode = 0;
-+ mchbar_write32(DDR_DATA_ch_CONTROL_0(channel), data_control_0.raw);
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++) {
-+ const uint8_t feedback = get_data_train_feedback(channel, byte);
-+ struct vref_train_data *curr_data = &vref_data[channel][byte];
-+ curr_data->low_mask &= feedback;
-+ curr_data->sum_bits = -popcnt(feedback);
-+ }
-+ }
-+
-+ /* Program settings for Vref and SampOffset = -7 (8 - 7) */
-+ mchbar_write32(DDR_DATA_RX_OFFSET_VDQ, 0x11111111);
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ /* Propagate delay values (without a read command) */
-+ union ddr_data_control_0_reg data_control_0 = {
-+ .raw = ctrl->dq_control_0[channel],
-+ };
-+ data_control_0.read_rf_rd = 1;
-+ data_control_0.read_rf_wr = 0;
-+ data_control_0.read_rf_rank = 0;
-+ data_control_0.force_odt_on = 1;
-+ data_control_0.samp_train_mode = 1;
-+ mchbar_write32(DDR_DATA_ch_CONTROL_0(channel), data_control_0.raw);
-+ udelay(1);
-+ data_control_0.samp_train_mode = 0;
-+ mchbar_write32(DDR_DATA_ch_CONTROL_0(channel), data_control_0.raw);
-+ printk(VREF_OFFSET_PLOT, "\t");
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++) {
-+ const uint8_t feedback = get_data_train_feedback(channel, byte);
-+ struct vref_train_data *curr_data = &vref_data[channel][byte];
-+ curr_data->high_mask |= feedback;
-+ curr_data->sum_bits += popcnt(feedback);
-+ printk(VREF_OFFSET_PLOT, "%d ", curr_data->sum_bits);
-+ if (curr_data->sum_bits > curr_data->best_sum) {
-+ curr_data->best_sum = curr_data->sum_bits;
-+ curr_data->best_vref = vref;
-+ ctrl->rxvref[channel][0][byte] = vref;
-+ } else if (curr_data->sum_bits == curr_data->best_sum) {
-+ curr_data->best_vref = vref;
-+ }
-+ }
-+ }
-+ }
-+ printk(BIOS_DEBUG, "\n\nHi-Lo (XOR):");
-+ enum raminit_status status = RAMINIT_STATUS_SUCCESS;
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ printk(BIOS_DEBUG, "\n C%u:", channel);
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++) {
-+ struct vref_train_data *const curr_data = &vref_data[channel][byte];
-+ const uint8_t bit_xor = curr_data->high_mask ^ curr_data->low_mask;
-+ printk(BIOS_DEBUG, "\t0x%02x", bit_xor);
-+ if (bit_xor == 0xff)
-+ continue;
-+
-+ /* Report an error if any bit did not change */
-+ status = RAMINIT_STATUS_SAMP_OFFSET_FAILURE;
-+ }
-+ }
-+ if (status)
-+ printk(BIOS_ERR, "\nUnexpected bit error in Vref offset training\n");
-+
-+ printk(BIOS_DEBUG, "\n\nRdVref:");
-+ change_1d_margin_multicast(ctrl, RdV, 0, 0, false, REG_FILE_USE_RANK);
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ printk(BIOS_DEBUG, "\n C%u:", channel);
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++) {
-+ struct vref_train_data *const curr_data = &vref_data[channel][byte];
-+ const int8_t vref_width =
-+ curr_data->best_vref - ctrl->rxvref[channel][0][byte];
-+
-+ /*
-+ * Step size for Rx Vref in DATA_OFFSET_TRAIN is about 3.9 mV
-+ * whereas Rx Vref step size in RX_TRAIN_RANK is about 7.8 mV
-+ */
-+ int8_t vref = ctrl->rxvref[channel][0][byte] + vref_width / 2;
-+ if (vref < 0)
-+ vref--;
-+ else
-+ vref++;
-+
-+ for (uint8_t rank = 0; rank < NUM_SLOTRANKS; rank++) {
-+ if (!rank_in_ch(ctrl, rank, channel))
-+ continue;
-+
-+ ctrl->rxvref[channel][rank][byte] = vref / 2;
-+ update_rxt(ctrl, channel, rank, byte, RXT_RESTORE, 0);
-+ }
-+ printk(BIOS_DEBUG, "\t% 4d", ctrl->rxvref[channel][0][byte]);
-+ }
-+ }
-+ printk(BIOS_DEBUG, "\n\n");
-+ return status;
-+}
-+
-+/**
-+ * LPDDR has an additional bit for DQS per each byte.
-+ *
-+ * TODO: The DQS value must be written into Data Control 2.
-+ */
-+#define NUM_OFFSET_TRAIN_BITS (NUM_BITS + 1)
-+
-+#define PLOT_CH_SPACE " "
-+
-+struct samp_train_data {
-+ uint8_t first_zero;
-+ uint8_t last_one;
-+};
-+
-+static void train_samp_offset(struct sysinfo *ctrl)
-+{
-+ const uint8_t max_train_bits = ctrl->lpddr ? NUM_OFFSET_TRAIN_BITS : NUM_BITS;
-+
-+ struct samp_train_data samp_data[NUM_CHANNELS][NUM_LANES][NUM_OFFSET_TRAIN_BITS] = {0};
-+
-+ printk(BIOS_DEBUG, "Channel ");
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ printk(BIOS_DEBUG, "%u ", channel); /* Same length as PLOT_CH_SPACE */
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++)
-+ printk(BIOS_DEBUG, " %s ", ctrl->lpddr ? " " : "");
-+ }
-+ printk(BIOS_DEBUG, "\nByte ");
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++)
-+ printk(BIOS_DEBUG, "%u %s ", byte, ctrl->lpddr ? " " : "");
-+
-+ printk(BIOS_DEBUG, PLOT_CH_SPACE);
-+ }
-+ printk(SAMP_OFFSET_PLOT, "\nBits ");
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++)
-+ printk(SAMP_OFFSET_PLOT, "01234567%s ", ctrl->lpddr ? "S" : "");
-+
-+ printk(SAMP_OFFSET_PLOT, PLOT_CH_SPACE);
-+ }
-+ printk(SAMP_OFFSET_PLOT, "\n SAmp\n");
-+ for (uint8_t samp_offset = 1; samp_offset <= 15; samp_offset++) {
-+ printk(SAMP_OFFSET_PLOT, "% 5d\t", samp_offset);
-+
-+ uint32_t rx_offset_vdq = 0;
-+ for (uint8_t bit = 0; bit < NUM_BITS; bit++) {
-+ rx_offset_vdq += samp_offset << (4 * bit);
-+ }
-+ mchbar_write32(DDR_DATA_RX_OFFSET_VDQ, rx_offset_vdq);
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ /* Propagate delay values (without a read command) */
-+ union ddr_data_control_0_reg data_control_0 = {
-+ .raw = ctrl->dq_control_0[channel],
-+ };
-+ data_control_0.read_rf_rd = 1;
-+ data_control_0.read_rf_wr = 0;
-+ data_control_0.read_rf_rank = 0;
-+ data_control_0.force_odt_on = 1;
-+ data_control_0.samp_train_mode = 1;
-+ mchbar_write32(DDR_DATA_ch_CONTROL_0(channel), data_control_0.raw);
-+ udelay(1);
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++) {
-+ const uint32_t feedback =
-+ get_data_train_feedback(channel, byte);
-+
-+ for (uint8_t bit = 0; bit < max_train_bits; bit++) {
-+ struct samp_train_data *const curr_data =
-+ &samp_data[channel][byte][bit];
-+ const bool result = feedback & BIT(bit);
-+ if (result) {
-+ curr_data->last_one = samp_offset;
-+ } else if (curr_data->first_zero == 0) {
-+ curr_data->first_zero = samp_offset;
-+ }
-+ printk(SAMP_OFFSET_PLOT, result ? "." : "#");
-+ }
-+ printk(SAMP_OFFSET_PLOT, " ");
-+ }
-+ printk(SAMP_OFFSET_PLOT, PLOT_CH_SPACE);
-+ data_control_0.samp_train_mode = 0;
-+ mchbar_write32(DDR_DATA_ch_CONTROL_0(channel), data_control_0.raw);
-+ }
-+ printk(SAMP_OFFSET_PLOT, "\n");
-+ }
-+ printk(BIOS_DEBUG, "\nBitSAmp ");
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++) {
-+ uint32_t rx_offset_vdq = 0;
-+ for (uint8_t bit = 0; bit < max_train_bits; bit++) {
-+ struct samp_train_data *const curr_data =
-+ &samp_data[channel][byte][bit];
-+
-+ uint8_t vref = curr_data->first_zero + curr_data->last_one;
-+ vref = clamp_u8(0, vref / 2, 15);
-+ /*
-+ * Check for saturation conditions to make sure
-+ * we are as close as possible to Vdd/2 (750 mV).
-+ */
-+ if (curr_data->first_zero == 0)
-+ vref = 15;
-+ if (curr_data->last_one == 0)
-+ vref = 0;
-+
-+ ctrl->rxdqvrefpb[channel][0][byte][bit].center = vref;
-+ rx_offset_vdq += vref & 0xf << (4 * bit);
-+ printk(BIOS_DEBUG, "%x", vref);
-+ }
-+ mchbar_write32(RX_OFFSET_VDQ(channel, byte), rx_offset_vdq);
-+ printk(BIOS_DEBUG, " ");
-+ download_regfile(ctrl, channel, 1, 0, REG_FILE_USE_RANK, 0, 1, 0);
-+ }
-+ printk(BIOS_DEBUG, PLOT_CH_SPACE);
-+ }
-+ printk(BIOS_DEBUG, "\n");
-+}
-+
-+enum raminit_status train_sense_amp_offset(struct sysinfo *ctrl)
-+{
-+ printk(BIOS_DEBUG, "Stage 1: Vref offset training\n");
-+ const enum raminit_status status = train_vref_offset(ctrl);
-+
-+ printk(BIOS_DEBUG, "Stage 2: Samp offset training\n");
-+ train_samp_offset(ctrl);
-+
-+ /* Clean up after test */
-+ for (uint8_t channel = 0; channel < NUM_CHANNELS; channel++) {
-+ if (!does_ch_exist(ctrl, channel))
-+ continue;
-+
-+ mchbar_write32(DDR_DATA_ch_CONTROL_0(channel), ctrl->dq_control_0[channel]);
-+ for (uint8_t byte = 0; byte < ctrl->lanes; byte++)
-+ mchbar_write32(DQ_CONTROL_2(channel, byte),
-+ ctrl->dq_control_2[channel][byte]);
-+ }
-+ io_reset();
-+ return status;
-+}
-diff --git a/src/northbridge/intel/haswell/registers/mchbar.h b/src/northbridge/intel/haswell/registers/mchbar.h
-index 49a215aa71..1a168a3fc8 100644
---- a/src/northbridge/intel/haswell/registers/mchbar.h
-+++ b/src/northbridge/intel/haswell/registers/mchbar.h
-@@ -18,6 +18,8 @@
- #define RX_TRAIN_ch_r_b(ch, rank, byte) _DDRIO_C_R_B(0x0000, ch, rank, byte)
- #define TX_TRAIN_ch_r_b(ch, rank, byte) _DDRIO_C_R_B(0x0020, ch, rank, byte)
-
-+#define RX_OFFSET_VDQ(ch, byte) _DDRIO_C_R_B(0x004c, ch, 0, byte)
-+
- #define DDR_DATA_TRAIN_FEEDBACK(ch, byte) _DDRIO_C_R_B(0x0054, ch, 0, byte)
-
- #define DQ_CONTROL_1(ch, byte) _DDRIO_C_R_B(0x0060, ch, 0, byte)
---
-2.39.2
-