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_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 */