soc/intel/apollolake: Update default LPDDR4 CA ODT config

Update default ODT config to have correct CA ODT settings as the
current defaults are incorrect for all the current apollolake designs.
All the current designs pull both A and B channels' LPDDR4 modules' ODT
pins to 1.1V. Therefore, the correct impedance setting needs to be
applied.

In order for the settings to take effect one needs to clear the
memory training cache in deployed systems. Trigger this by bumping
the memory setting version for the SoC.

If needed in the future support for allowing the override of this
setting from the mainboard should be straight forward. It's just not
necessary at this time.

BUG=b:37687843
TEST=BAT test, warm, reboot, S3 cycle test

Change-Id: I9a2f7636b46492a9d08472a0752cdf1f86a72e15
Signed-off-by: Ravi Sarawadi <ravishankar.sarawadi@intel.com>
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/19397
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins)

1 files changed, 14 insertions, 0 deletions

diff --git a/src/soc/intel/apollolake/include/soc/meminit.h b/src/soc/intel/apollolake/include/soc/meminit.h
index 45b20a0989..339d2b1fac 100644
--- a/src/soc/intel/apollolake/include/soc/meminit.h
+++ b/src/soc/intel/apollolake/include/soc/meminit.h
@@ -69,6 +69,20 @@ enum {
 	LP4_16Gb_DENSITY,
 };
 
+/*
+ * ODT settings :
+ * If ODT PIN to LP4 DRAM is pulled HIGH for ODT_A, and HIGH for ODT_B,
+ * choose ODT_AB_HIGH_HIGH. If ODT PIN to LP4 DRAM is pulled HIGH for ODT_A,
+ * and LOW for ODT_B, choose ODT_AB_HIGH_LOW.
+ *
+ * Note that the enum values correspond to the interpreted UPD fields
+ * witihn Ch[3:0]_OdtConfig parameters.
+*/
+enum {
+	ODT_A_B_HIGH_LOW = 0 << 1,
+	ODT_A_B_HIGH_HIGH = 1 << 1,
+};
+
 /* Provide bit swizzling per DQS and byte swapping within a channel. */
 struct lpddr4_chan_swizzle_cfg {
 	uint8_t dqs[LP4_NUM_BYTE_LANES][DQ_BITS_PER_DQS];