Florian Zumbiehl just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/382
-gerrit
commit c7f56fd75e8ad765d575d7d151ebf69fb6f884fe Author: Florian Zumbiehl florz@florz.de Date: Tue Nov 1 20:19:03 2011 +0100
support for setting the Memory DQ Drive Strength register in amdk8 raminit
make sure DRAM drive strength is not reduced
Change-Id: Ic68c10b75bd0217540fb1f55dded1f9d7f5e8aea Signed-off-by: Florian Zumbiehl florz@florz.de --- src/northbridge/amd/amdk8/pre_f.h | 6 ++++++ src/northbridge/amd/amdk8/raminit.c | 12 ++++++++++++ 2 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/src/northbridge/amd/amdk8/pre_f.h b/src/northbridge/amd/amdk8/pre_f.h index dae2d97..0d5f6fa 100644 --- a/src/northbridge/amd/amdk8/pre_f.h +++ b/src/northbridge/amd/amdk8/pre_f.h @@ -157,6 +157,12 @@ #define DCH_RDPREAMBLE_BASE ((2<<1)+0) /* 2.0 ns */ #define DCH_RDPREAMBLE_MIN ((2<<1)+0) /* 2.0 ns */ #define DCH_RDPREAMBLE_MAX ((9<<1)+1) /* 9.5 ns */ +#define DCH_DQ_DRV_STRENGTH_SHIFT 13 +#define DCH_DQ_DRV_STRENGTH_MASK 3 +#define DCH_DQ_DRV_STRENGTH_0 0 +#define DCH_DQ_DRV_STRENGTH_15 1 +#define DCH_DQ_DRV_STRENGTH_30 2 +#define DCH_DQ_DRV_STRENGTH_50 3 #define DCH_IDLE_LIMIT_SHIFT 16 #define DCH_IDLE_LIMIT_MASK 0x7 #define DCH_IDLE_LIMIT_0 0 diff --git a/src/northbridge/amd/amdk8/raminit.c b/src/northbridge/amd/amdk8/raminit.c index 02c764d..e09075f 100644 --- a/src/northbridge/amd/amdk8/raminit.c +++ b/src/northbridge/amd/amdk8/raminit.c @@ -2201,6 +2201,18 @@ static void sdram_set_spd_registers(const struct mem_controller *ctrl) printk(BIOS_DEBUG, "No memory for this cpu\n"); return; } + + if (!is_cpu_pre_e0()) { + uint32_t dch; + + // see also erratum 114, essentially: never ever + // set to anything but 0 + dch = pci_read_config32(ctrl->f2, DRAM_CONFIG_HIGH); + dch &= ~(DCH_DQ_DRV_STRENGTH_MASK << DCH_DQ_DRV_STRENGTH_SHIFT); + dch |= DCH_DQ_DRV_STRENGTH_0 << DCH_DQ_DRV_STRENGTH_SHIFT; + pci_write_config32(ctrl->f2, DRAM_CONFIG_HIGH, dch); + } + dimm_mask = spd_enable_2channels(ctrl, dimm_mask); if (dimm_mask < 0) goto hw_spd_err;