[Skiboot] [PATCH 2/2] platform/mihawk: Tune equalization settings for opencapi

[Frederic Barrat]

The Bittware 250SOC adapter on Mihawk was showing a high count of CRC
errors on one of the opencapi slots. The PHY team suggested new
equalization settings to correct the errors.

All existing adapters have been tested on mihawk to make sure the
settings are compatible. However, the new settings should not be used
on platforms other than mihawk.

The changes specific to mihawk are:
- Update the tx_ffe_pre_coeff and tx_ffe_post_coeff input parameters
  used during zcal
- turn off the tx_ffe_boost parameter through scom

Signed-off-by: Frederic Barrat <fbarrat at linux.ibm.com>
Cc: skiboot-stable at lists.ozlabs.org # skiboot-op940.x
---
 hw/npu2-hw-procedures.c   | 25 ++++++++++++++++++-------
 include/npu2.h            |  2 ++
 platforms/astbmc/mihawk.c |  1 +
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/hw/npu2-hw-procedures.c b/hw/npu2-hw-procedures.c
index 890b25a8..95a0f9dc 100644
--- a/hw/npu2-hw-procedures.c
+++ b/hw/npu2-hw-procedures.c
@@ -78,6 +78,7 @@ static struct npu2_phy_reg NPU2_PHY_TX_ZCAL_DONE	       = {0x3c1, 50, 1};
 static struct npu2_phy_reg NPU2_PHY_TX_ZCAL_ERROR	       = {0x3c1, 51, 1};
 static struct npu2_phy_reg NPU2_PHY_TX_ZCAL_N		       = {0x3c3, 48, 9};
 static struct npu2_phy_reg NPU2_PHY_TX_ZCAL_P		       = {0x3c5, 48, 9};
+static struct npu2_phy_reg NPU2_PHY_TX_FFE_BOOST_EN	       = {0x34b, 59, 1};
 static struct npu2_phy_reg NPU2_PHY_TX_PSEG_PRE_EN	       = {0x34d, 51, 5};
 static struct npu2_phy_reg NPU2_PHY_TX_PSEG_PRE_SELECT	       = {0x34d, 56, 5};
 static struct npu2_phy_reg NPU2_PHY_TX_NSEG_PRE_EN	       = {0x34f, 51, 5};
@@ -498,10 +499,11 @@ static uint32_t phy_tx_zcal_wait(struct npu2_dev *ndev)
 	return PROCEDURE_NEXT;
 }
 
-#define MARGIN_RATIO		(0)
-#define FFE_PRE_COEFF		(0)
-#define FFE_POST_COEFF		(0)
 
+int ffe_pre_coeff = 0;
+int ffe_post_coeff = 0;
+
+#define MARGIN_RATIO		(0)
 #define PRE_WIDTH		(5)
 #define POST_WIDTH		(7)
 #define MAIN_WIDTH		(7)
@@ -565,8 +567,8 @@ static uint32_t phy_tx_zcal_calculate(struct npu2_dev *ndev)
 		return PROCEDURE_COMPLETE | PROCEDURE_FAILED;
 
 	p_value = zcal_p - TOTAL_X2_MAX;
-	p_precursor_select = (p_value * FFE_PRE_COEFF)/128;
-	p_postcursor_select = (p_value * FFE_POST_COEFF)/128;
+	p_precursor_select = (p_value * ffe_pre_coeff)/128;
+	p_postcursor_select = (p_value * ffe_post_coeff)/128;
 	margin_pu_select = (p_value * MARGIN_RATIO)/256;
 
 	if (p_value % 2) {
@@ -587,8 +589,8 @@ static uint32_t phy_tx_zcal_calculate(struct npu2_dev *ndev)
 	}
 
 	n_value = zcal_n - TOTAL_X2_MAX;
-	n_precursor_select = (n_value * FFE_PRE_COEFF)/128;
-	n_postcursor_select = (n_value * FFE_POST_COEFF)/128;
+	n_precursor_select = (n_value * ffe_pre_coeff)/128;
+	n_postcursor_select = (n_value * ffe_post_coeff)/128;
 	margin_pd_select = (p_value * MARGIN_RATIO)/256;
 
 	if (n_value % 2) {
@@ -1065,3 +1067,12 @@ void npu2_opencapi_phy_prbs31(struct npu2_dev *dev)
 {
 	phy_write(dev, &NPU2_PHY_TX_DRV_DATA_PATTERN_GCRMSG, 0xD);
 }
+
+void mihawk_phy_setup(struct npu2_dev *dev)
+{
+	/* Tune equalization settings */
+	NPU2DEVINF(dev, "Enabling Mihawk-specific PHY setup\n");
+	phy_write(dev, &NPU2_PHY_TX_FFE_BOOST_EN, 0);
+	ffe_pre_coeff = 0x3;
+	ffe_post_coeff = 0x14;
+}
diff --git a/include/npu2.h b/include/npu2.h
index eb7c4558..cab1e7ac 100644
--- a/include/npu2.h
+++ b/include/npu2.h
@@ -243,6 +243,8 @@ int64_t npu2_freeze_status(struct phb *phb __unused,
 			   uint16_t *severity __unused);
 void npu2_dump_scoms(int chip_id);
 
+void mihawk_phy_setup(struct npu2_dev *dev);
+
 int64_t npu2_init_context(struct phb *phb, uint64_t msr, uint64_t bdf);
 int64_t npu2_destroy_context(struct phb *phb, uint64_t bdf);
 int64_t npu2_map_lpar(struct phb *phb, uint64_t bdf, uint64_t lparid,
diff --git a/platforms/astbmc/mihawk.c b/platforms/astbmc/mihawk.c
index 8971b407..813ab406 100644
--- a/platforms/astbmc/mihawk.c
+++ b/platforms/astbmc/mihawk.c
@@ -157,6 +157,7 @@ static const struct platform_ocapi mihawk_ocapi = {
         .i2c_presence_brick5 = 0, /* unused */
         .odl_phy_swap        = true,
 	.ocapi_slot_label    = mihawk_ocapi_slot_label,
+	.phy_setup           = mihawk_phy_setup,
 };
 
 static const struct slot_table_entry P1E1A_x8_PLX8748_RiserA_down[] = {
-- 
2.25.1