[Skiboot] [PATCH 3/3] npu2/hw-procedures: Fix parallel zcal for opencapi

[Frederic Barrat]

For opencapi, we currently do impedance calibration when initializing
the PHY for the device, which could run in parallel if we were rich
and had multiple opencapi devices. But if 2 devices are on the same
obus, the 2 calibration sequences could overlap, which likely yields
bad results and is useless anyway since it only needs to be done once
per obus.

This patch splits the opencapi PHY reset in 2 parts:
- a 'init' part called serially at boot. That's when zcal is done. If
  we have 2 devices on the same socket, the zcal won't be redone,
  since we're called serially and we'll see it has already be done for
  the obus
- a 'reset' part called during fundamental reset as a prereq for link
  training. It does the PHY setup for a set of lanes and the dccal.

The PHY team confirmed there's no dependency between zcal and the
other reset steps and it can be moved earlier.

Signed-off-by: Frederic Barrat <fbarrat at linux.ibm.com>
---
 hw/npu2-hw-procedures.c | 7 +++++--
 hw/npu2-opencapi.c      | 5 +++--
 include/npu2.h          | 3 ++-
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/hw/npu2-hw-procedures.c b/hw/npu2-hw-procedures.c
index 2f330957..b671b8ac 100644
--- a/hw/npu2-hw-procedures.c
+++ b/hw/npu2-hw-procedures.c
@@ -1017,17 +1017,20 @@ void npu2_opencapi_bump_ui_lane(struct npu2_dev *dev)
 	}
 }
 
-void npu2_opencapi_phy_setup(struct npu2_dev *dev)
+void npu2_opencapi_phy_init(struct npu2_dev *dev)
 {
+	run_procedure(dev, 5); /* procedure_phy_tx_zcal */
 	/*
 	 * This is only required for OpenCAPI - Hostboot tries to set this
 	 * on systems where it can tell a link is OpenCAPI, but for
 	 * Witherspoon it needs to be done in skiboot after device detection.
 	 */
 	phy_write(dev, &NPU2_PHY_RX_RC_ENABLE_AUTO_RECAL, 0x1);
+}
 
+void npu2_opencapi_phy_reset(struct npu2_dev *dev)
+{
 	run_procedure(dev, 4); /* procedure_phy_reset */
-	run_procedure(dev, 5); /* procedure_phy_tx_zcal */
 	run_procedure(dev, 6); /* procedure_phy_rx_dccal */
 }
 
diff --git a/hw/npu2-opencapi.c b/hw/npu2-opencapi.c
index b2740f38..090223e2 100644
--- a/hw/npu2-opencapi.c
+++ b/hw/npu2-opencapi.c
@@ -1194,7 +1194,7 @@ static int64_t npu2_opencapi_freset(struct pci_slot *slot)
 		}
 		dev->train_need_fence = true;
 		slot->link_retries = OCAPI_LINK_TRAINING_RETRIES;
-		npu2_opencapi_phy_setup(dev);
+		npu2_opencapi_phy_reset(dev);
 		/* fall-through */
 	case OCAPI_SLOT_FRESET_INIT:
 		assert_odl_reset(chip_id, dev->brick_index);
@@ -1603,7 +1603,7 @@ static int setup_irq(struct npu2 *p)
 
 static void setup_debug_training_state(struct npu2_dev *dev)
 {
-	npu2_opencapi_phy_setup(dev);
+	npu2_opencapi_phy_reset(dev);
 
 	switch (npu2_ocapi_training_state) {
 	case NPU2_TRAIN_PRBS31:
@@ -1675,6 +1675,7 @@ static void setup_device(struct npu2_dev *dev)
 	/* Procedure 13.1.3.9 - AFU Config BARs */
 	setup_afu_config_bars(dev->npu->chip_id, dev->npu->xscom_base, dev);
 	setup_perf_counters(dev);
+	npu2_opencapi_phy_init(dev);
 
 	set_fence_control(dev->npu->chip_id, dev->npu->xscom_base, dev->brick_index, 0b00);
 
diff --git a/include/npu2.h b/include/npu2.h
index b62d1748..a2bcc450 100644
--- a/include/npu2.h
+++ b/include/npu2.h
@@ -224,7 +224,8 @@ void npu2_set_link_flag(struct npu2_dev *ndev, uint8_t flag);
 void npu2_clear_link_flag(struct npu2_dev *ndev, uint8_t flag);
 uint32_t reset_ntl(struct npu2_dev *ndev);
 extern int nv_zcal_nominal;
-void npu2_opencapi_phy_setup(struct npu2_dev *dev);
+void npu2_opencapi_phy_init(struct npu2_dev *dev);
+void npu2_opencapi_phy_reset(struct npu2_dev *dev);
 void npu2_opencapi_phy_prbs31(struct npu2_dev *dev);
 void npu2_opencapi_bump_ui_lane(struct npu2_dev *dev);
 int64_t npu2_freeze_status(struct phb *phb __unused,
-- 
2.19.1