nb/intel/sandybridge: Only use write Vref if supported

Only some Ivy Bridge SKUs support write Vref control.

Change-Id: I4e606c69c6758d909946da43c3d243e3af8833cf
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47747
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
This commit is contained in:
Angel Pons 2020-11-19 12:53:36 +01:00 committed by Patrick Georgi
parent 09fc4b90eb
commit 9fbb1b096f
2 changed files with 8 additions and 0 deletions

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@ -2459,6 +2459,13 @@ int discover_timC_write(ramctr_timing *ctrl)
int upper[NUM_CHANNELS][NUM_SLOTRANKS][NUM_LANES];
int channel, slotrank, lane;
/* Changing the write Vref is only supported on some Ivy Bridge SKUs */
if (!IS_IVY_CPU(ctrl->cpu))
return 0;
if (!(pci_read_config32(HOST_BRIDGE, CAPID0_A) & CAPID_WRTVREF))
return 0;
FOR_ALL_CHANNELS FOR_ALL_POPULATED_RANKS FOR_ALL_LANES {
lower[channel][slotrank][lane] = 0;
upper[channel][slotrank][lane] = MAX_TIMC;

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@ -52,6 +52,7 @@
#define CAPID_ECCDIS (1 << 25)
#define CAPID_DDPCD (1 << 14)
#define CAPID_PDCD (1 << 12)
#define CAPID_WRTVREF (1 << 1)
#define CAPID_DDRSZ(x) (((x) >> 19) & 0x3)
#define CAPID0_B 0xe8 /* Capabilities Register B */