From 4e0cd82b5b96ac729654a19eff445b0b4cc10350 Mon Sep 17 00:00:00 2001 From: Patrick Rudolph Date: Fri, 1 May 2020 18:35:36 +0200 Subject: nb/intel/sandybridge/raminit: Add comments Add comments found when testing ECC scrubbing code. This is a cosmetic change. Change-Id: I7975f6070c2002930eec407a6b101a1295495b25 Signed-off-by: Patrick Rudolph Reviewed-on: https://review.coreboot.org/c/coreboot/+/40947 Reviewed-by: Paul Menzel Reviewed-by: Angel Pons Tested-by: build bot (Jenkins) --- src/northbridge/intel/sandybridge/raminit_common.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/src/northbridge/intel/sandybridge/raminit_common.c b/src/northbridge/intel/sandybridge/raminit_common.c index 126acbe65e..3527c8e520 100644 --- a/src/northbridge/intel/sandybridge/raminit_common.c +++ b/src/northbridge/intel/sandybridge/raminit_common.c @@ -319,8 +319,14 @@ void dram_dimm_mapping(ramctr_timing *ctrl) reg |= (dimmB->width / 8 - 1) << 20; } - reg |= 1 << 21; /* Rank interleave */ - reg |= 1 << 22; /* Enhanced interleave */ + /* + * Rank interleave: Bit 16 of the physical address space sets + * the rank to use in a dual single rank DIMM configuration. + * That results in every 64KiB being interleaved between two ranks. + */ + reg |= 1 << 21; + /* Enhanced interleave */ + reg |= 1 << 22; if ((dimmA && (dimmA->ranks > 0)) || (dimmB && (dimmB->ranks > 0))) { ctrl->mad_dimm[channel] = reg; -- cgit v1.2.3