[Skiboot] [PATCH v2] 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
---

Vasant, Oliver: this is for mihawk and should not have any side effect
on other plaforms. At this point, I'm thoroughly confused whether it
should go to the skiboot-op940.x branch, as I'm hearing conflicting
signals. In any case, it should go to master for our own good and be
able to use our lab systems. Time will sort out the skiboot-op940.x
status.



Changelog:
v2: avoid globals (Andrew)



 hw/npu2-hw-procedures.c   | 23 +++++++++++++++++++----
 include/platform.h        |  7 +++++++
 platforms/astbmc/mihawk.c |  7 +++++++
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/hw/npu2-hw-procedures.c b/hw/npu2-hw-procedures.c
index 6236380a..fb88dfdf 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};
@@ -533,6 +534,8 @@ static uint32_t therm_with_half(uint32_t dec, uint8_t width)
 static uint32_t phy_tx_zcal_calculate(struct npu2_dev *ndev)
 {
 	int p_value, n_value;
+	int ffe_pre_coeff = FFE_PRE_COEFF;
+	int ffe_post_coeff = FFE_POST_COEFF;
 	uint32_t zcal_n;
 	uint32_t zcal_p;
 	uint32_t p_main_enable = MAIN_X2_MAX;
@@ -564,9 +567,15 @@ static uint32_t phy_tx_zcal_calculate(struct npu2_dev *ndev)
 	    (zcal_p < ZCAL_MIN) || (zcal_p > ZCAL_MAX))
 		return PROCEDURE_COMPLETE | PROCEDURE_FAILED;
 
+	if (ndev->type == NPU2_DEV_TYPE_OPENCAPI &&
+	    platform.ocapi->phy_setup) {
+		ffe_pre_coeff = platform.ocapi->phy_setup->tx_ffe_pre_coeff;
+		ffe_post_coeff = platform.ocapi->phy_setup->tx_ffe_post_coeff;
+	}
+
 	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 +596,8 @@ 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) {
@@ -1020,6 +1029,12 @@ void npu2_opencapi_bump_ui_lane(struct npu2_dev *dev)
 
 void npu2_opencapi_phy_init(struct npu2_dev *dev)
 {
+	if (platform.ocapi->phy_setup) {
+		OCAPIINF(dev, "Enabling platform-specific PHY setup\n");
+		phy_write(dev, &NPU2_PHY_TX_FFE_BOOST_EN,
+			  platform.ocapi->phy_setup->tx_ffe_boost_en);
+	}
+
 	run_procedure(dev, 5); /* procedure_phy_tx_zcal */
 	/*
 	 * This is only required for OpenCAPI - Hostboot tries to set this
diff --git a/include/platform.h b/include/platform.h
index 6aa263ae..ef93278b 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -47,6 +47,12 @@ struct bmc_platform {
 	const struct bmc_sw_config *sw;
 };
 
+struct ocapi_phy_setup {
+	int tx_ffe_pre_coeff;
+	int tx_ffe_post_coeff;
+	int tx_ffe_boost_en;
+};
+
 /* OpenCAPI platform-specific I2C information */
 struct platform_ocapi {
 	uint8_t i2c_engine;		/* I2C engine number */
@@ -64,6 +70,7 @@ struct platform_ocapi {
 	bool odl_phy_swap;		/* Swap ODL1 to use brick 2 rather than
 					 * brick 1 lanes */
 	const char *(*ocapi_slot_label)(uint32_t chip_id, uint32_t brick_index);
+	const struct ocapi_phy_setup *phy_setup;
 };
 
 struct dt_node;
diff --git a/platforms/astbmc/mihawk.c b/platforms/astbmc/mihawk.c
index 8971b407..f3669ff3 100644
--- a/platforms/astbmc/mihawk.c
+++ b/platforms/astbmc/mihawk.c
@@ -142,6 +142,12 @@ static const char *mihawk_ocapi_slot_label(uint32_t chip_id,
 	return name;
 }
 
+static const struct ocapi_phy_setup mihawk_phy = {
+	.tx_ffe_pre_coeff = 0x3,
+	.tx_ffe_post_coeff = 0x14,
+	.tx_ffe_boost_en = 0,
+};
+
 static const struct platform_ocapi mihawk_ocapi = {
         .i2c_engine          = 1,
         .i2c_port            = 4,
@@ -157,6 +163,7 @@ 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,
 };
 
 static const struct slot_table_entry P1E1A_x8_PLX8748_RiserA_down[] = {
-- 
2.25.3