nb/intel/sandybridge: support more XMP timings
Tested with a pair of GSkill F3-1866C9-8GSR.
This makes sure in particular that we honor the CMD rate requested by
the XMP profile. This memory kit needs a CMD rate of 2 to be stable at
DDR3-1600 and up, even though it passes training at 1.
Also respect requested CWL to match vendor firmware and for a potential
increase in performance. The tested kit requests a tighter value than
the per-frequency table provides and has shown to be stable using that
setting.
Change-Id: I634bed764d76345c27f02a2fae5abb2d81b38fd9
Signed-off-by: Dan Elkouby <streetwalkermc@gmail.com>
Reviewed-on: https://review.coreboot.org/25664
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/sandybridge/raminit_common.c b/src/northbridge/intel/sandybridge/raminit_common.c
index 0a44220..5f6753f 100644
--- a/src/northbridge/intel/sandybridge/raminit_common.c
+++ b/src/northbridge/intel/sandybridge/raminit_common.c
@@ -160,6 +160,8 @@
ctrl->tWTR = MAX(ctrl->tWTR, dimm->tWTR);
ctrl->tRTP = MAX(ctrl->tRTP, dimm->tRTP);
ctrl->tFAW = MAX(ctrl->tFAW, dimm->tFAW);
+ ctrl->tCWL = MAX(ctrl->tCWL, dimm->tCWL);
+ ctrl->tCMD = MAX(ctrl->tCMD, dimm->tCMD);
}
if (!ctrl->cas_supported)
@@ -2350,12 +2352,16 @@
* will fail in write training.
* Workaround: Skip 1T in dual DIMM mode, that's only
* supported by a few DIMMs.
- * TODO: How to detect "1T" DIMMs ?
+ * Only try 1T mode for XMP DIMMs that request it in dual DIMM
+ * mode.
*
* Single DIMM per channel:
* Try command rate 1T and 2T
*/
cmdrate = ((ctrl->rankmap[channel] & 0x5) == 0x5);
+ if (ctrl->tCMD)
+ /* XMP gives the CMD rate in clock ticks, not ns */
+ cmdrate = MIN(DIV_ROUND_UP(ctrl->tCMD, 256) - 1, 1);
for (; cmdrate < 2; cmdrate++) {
err = try_cmd_stretch(ctrl, channel, cmdrate << 1);
diff --git a/src/northbridge/intel/sandybridge/raminit_common.h b/src/northbridge/intel/sandybridge/raminit_common.h
index ab6e592..1f32dcd 100644
--- a/src/northbridge/intel/sandybridge/raminit_common.h
+++ b/src/northbridge/intel/sandybridge/raminit_common.h
@@ -94,6 +94,8 @@
u32 tWTR;
u32 tRTP;
u32 tFAW;
+ u32 tCWL;
+ u32 tCMD;
/* Latencies in terms of clock cycles
* They are saved separately as they are needed for DRAM MRS commands*/
u8 CAS; /* CAS read latency */
diff --git a/src/northbridge/intel/sandybridge/raminit_ivy.c b/src/northbridge/intel/sandybridge/raminit_ivy.c
index 675ac71..19dea2f 100644
--- a/src/northbridge/intel/sandybridge/raminit_ivy.c
+++ b/src/northbridge/intel/sandybridge/raminit_ivy.c
@@ -479,7 +479,10 @@
/* DLL_CONFIG_MDLL_W_TIMER */
ctrl->reg_5064b0 = (128000 / ctrl->tCK) + 3;
- ctrl->CWL = get_CWL(ctrl->tCK);
+ if (ctrl->tCWL)
+ ctrl->CWL = DIV_ROUND_UP(ctrl->tCWL, ctrl->tCK);
+ else
+ ctrl->CWL = get_CWL(ctrl->tCK);
printk(BIOS_DEBUG, "Selected CWL latency : %uT\n", ctrl->CWL);
/* Find tRCD */
diff --git a/src/northbridge/intel/sandybridge/raminit_sandy.c b/src/northbridge/intel/sandybridge/raminit_sandy.c
index 3acc563..99c107e 100644
--- a/src/northbridge/intel/sandybridge/raminit_sandy.c
+++ b/src/northbridge/intel/sandybridge/raminit_sandy.c
@@ -251,7 +251,10 @@
/* DLL_CONFIG_MDLL_W_TIMER */
ctrl->reg_5064b0 = (128000 / ctrl->tCK) + 3;
- ctrl->CWL = get_CWL(ctrl->tCK);
+ if (ctrl->tCWL)
+ ctrl->CWL = DIV_ROUND_UP(ctrl->tCWL, ctrl->tCK);
+ else
+ ctrl->CWL = get_CWL(ctrl->tCK);
printk(BIOS_DEBUG, "Selected CWL latency : %uT\n", ctrl->CWL);
/* Find tRCD */