net/ngbe: fix flow control

[ upstream commit d19fa5a1f447244aa961a3cc8c52c9024f9109ab ]

Fix flow control high/low water limit.

Fixes: f40e9f0 ("net/ngbe: support flow control")

Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>

drivers/net/ngbe/base/ngbe_type.h

@@ -110,6 +110,46 @@ struct ngbe_fc_info {
 	enum ngbe_fc_mode requested_mode; /* FC mode requested by caller */
 };
 
+/* Flow Control Data Sheet defined values
+ * Calculation and defines taken from 802.1bb Annex O
+ */
+/* BitTimes (BT) conversion */
+#define NGBE_BT2KB(BT)         (((BT) + (8 * 1024 - 1)) / (8 * 1024))
+#define NGBE_B2BT(BT)          ((BT) * 8)
+
+/* Calculate Delay to respond to PFC */
+#define NGBE_PFC_D     672
+
+/* Calculate Cable Delay */
+#define NGBE_CABLE_DC  5556 /* Delay Copper */
+
+/* Calculate Interface Delay */
+#define NGBE_PHY_D     12800
+#define NGBE_MAC_D     4096
+#define NGBE_XAUI_D    (2 * 1024)
+
+#define NGBE_ID        (NGBE_MAC_D + NGBE_XAUI_D + NGBE_PHY_D)
+
+/* Calculate Delay incurred from higher layer */
+#define NGBE_HD        6144
+
+/* Calculate PCI Bus delay for low thresholds */
+#define NGBE_PCI_DELAY 10000
+
+/* Calculate delay value in bit times */
+#define NGBE_DV(_max_frame_link, _max_frame_tc) \
+			((36 * \
+			  (NGBE_B2BT(_max_frame_link) + \
+			   NGBE_PFC_D + \
+			   (2 * NGBE_CABLE_DC) + \
+			   (2 * NGBE_ID) + \
+			   NGBE_HD) / 25 + 1) + \
+			 2 * NGBE_B2BT(_max_frame_tc))
+
+#define NGBE_LOW_DV(_max_frame_tc) \
+			(2 * ((2 * NGBE_B2BT(_max_frame_tc) + \
+			      (36 * NGBE_PCI_DELAY / 25) + 1)))
+
 /* Statistics counters collected by the MAC */
 /* PB[] RxTx */
 struct ngbe_pb_stats {

drivers/net/ngbe/ngbe_ethdev.c

@@ -90,6 +90,7 @@ static int ngbe_dev_misc_interrupt_setup(struct rte_eth_dev *dev);
 static int ngbe_dev_rxq_interrupt_setup(struct rte_eth_dev *dev);
 static void ngbe_dev_interrupt_handler(void *param);
 static void ngbe_configure_msix(struct rte_eth_dev *dev);
+static void ngbe_pbthresh_set(struct rte_eth_dev *dev);
 
 #define NGBE_SET_HWSTRIP(h, q) do {\
 		uint32_t idx = (q) / (sizeof((h)->bitmap[0]) * NBBY); \
@@ -1020,6 +1021,7 @@ ngbe_dev_start(struct rte_eth_dev *dev)
 	}
 
 	hw->mac.setup_pba(hw);
+	ngbe_pbthresh_set(dev);
 	ngbe_configure_port(dev);
 
 	err = ngbe_dev_rxtx_start(dev);
@@ -2340,6 +2342,93 @@ ngbe_flow_ctrl_set(struct rte_eth_dev *dev, struct rte_eth_fc_conf *fc_conf)
 	return -EIO;
 }
 
+/* Additional bittime to account for NGBE framing */
+#define NGBE_ETH_FRAMING 20
+
+/*
+ * ngbe_fc_hpbthresh_set - calculate high water mark for flow control
+ *
+ * @dv_id: device interface delay
+ * @pb: packet buffer to calculate
+ */
+static s32
+ngbe_fc_hpbthresh_set(struct rte_eth_dev *dev)
+{
+	struct ngbe_hw *hw = ngbe_dev_hw(dev);
+	struct rte_pci_device *pci_dev = RTE_ETH_DEV_TO_PCI(dev);
+	u32 max_frame_size, tc, dv_id, rx_pb;
+	s32 kb, marker;
+
+	/* Calculate max LAN frame size */
+	max_frame_size = rd32m(hw, NGBE_FRMSZ, NGBE_FRMSZ_MAX_MASK);
+	tc = max_frame_size + NGBE_ETH_FRAMING;
+
+	/* Calculate delay value for device */
+	dv_id = NGBE_DV(tc, tc);
+
+	/* Loopback switch introduces additional latency */
+	if (pci_dev->max_vfs)
+		dv_id += NGBE_B2BT(tc);
+
+	/* Delay value is calculated in bit times convert to KB */
+	kb = NGBE_BT2KB(dv_id);
+	rx_pb = rd32(hw, NGBE_PBRXSIZE) >> 10;
+
+	marker = rx_pb - kb;
+
+	/* It is possible that the packet buffer is not large enough
+	 * to provide required headroom. In this case throw an error
+	 * to user and do the best we can.
+	 */
+	if (marker < 0) {
+		PMD_DRV_LOG(WARNING, "Packet Buffer can not provide enough headroom to support flow control.");
+		marker = tc + 1;
+	}
+
+	return marker;
+}
+
+/*
+ * ngbe_fc_lpbthresh_set - calculate low water mark for flow control
+ *
+ * @dv_id: device interface delay
+ */
+static s32
+ngbe_fc_lpbthresh_set(struct rte_eth_dev *dev)
+{
+	struct ngbe_hw *hw = ngbe_dev_hw(dev);
+	u32 max_frame_size, tc, dv_id;
+	s32 kb;
+
+	/* Calculate max LAN frame size */
+	max_frame_size = rd32m(hw, NGBE_FRMSZ, NGBE_FRMSZ_MAX_MASK);
+	tc = max_frame_size + NGBE_ETH_FRAMING;
+
+	/* Calculate delay value for device */
+	dv_id = NGBE_LOW_DV(tc);
+
+	/* Delay value is calculated in bit times convert to KB */
+	kb = NGBE_BT2KB(dv_id);
+
+	return kb;
+}
+
+/*
+ * ngbe_pbthresh_setup - calculate and setup high low water marks
+ */
+static void
+ngbe_pbthresh_set(struct rte_eth_dev *dev)
+{
+	struct ngbe_hw *hw = ngbe_dev_hw(dev);
+
+	hw->fc.high_water = ngbe_fc_hpbthresh_set(dev);
+	hw->fc.low_water = ngbe_fc_lpbthresh_set(dev);
+
+	/* Low water marks must not be larger than high water marks */
+	if (hw->fc.low_water > hw->fc.high_water)
+		hw->fc.low_water = 0;
+}
+
 int
 ngbe_dev_rss_reta_update(struct rte_eth_dev *dev,
 			  struct rte_eth_rss_reta_entry64 *reta_conf,