ixgbe: Allow Priority Flow Control settings to survive a device reset

When changing DCB parameters, ixgbe needs to have the MAC reset. The way
the flow control code is setup today, PFC will be disabled on a reset.
This patch adds a new flow control type for PFC, and then has the netlink
layer take care of toggling which type of flow control to enable.

Signed-off-by: Peter P Waskiewicz Jr <[e-mail]>
Signed-off-by: Jeff Kirsher <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ixgbe/ixgbe_common.c

···
 	 * 0: Flow control is completely disabled
 	 * 1: Rx flow control is enabled (we can receive pause frames,
 	 *    but not send pause frames).
-	 * 2:  Tx flow control is enabled (we can send pause frames but
-	 *     we do not support receiving pause frames).
+	 * 2: Tx flow control is enabled (we can send pause frames but
+	 *    we do not support receiving pause frames).
 	 * 3: Both Rx and Tx flow control (symmetric) are enabled.
+	 * 4: Priority Flow Control is enabled.
 	 * other: Invalid.
 	 */
 	switch (hw->fc.current_mode) {
···
 		mflcn_reg |= IXGBE_MFLCN_RFCE;
 		fccfg_reg |= IXGBE_FCCFG_TFCE_802_3X;
 		break;
+#ifdef CONFIG_DCB
+	case ixgbe_fc_pfc:
+		goto out;
+		break;
+#endif
 	default:
 		hw_dbg(hw, "Flow control param set incorrectly\n");
 		ret_val = -IXGBE_ERR_CONFIG;
···
 	 * 2:  Tx flow control is enabled (we can send pause frames but
 	 *     we do not support receiving pause frames).
 	 * 3:  Both Rx and Tx flow control (symmetric) are enabled.
+	 * 4:  Priority Flow Control is enabled.
 	 * other: Invalid.
 	 */
 	switch (hw->fc.current_mode) {
···
 		/* Flow control (both Rx and Tx) is enabled by SW override. */
 		reg |= (IXGBE_PCS1GANA_SYM_PAUSE | IXGBE_PCS1GANA_ASM_PAUSE);
 		break;
+#ifdef CONFIG_DCB
+	case ixgbe_fc_pfc:
+		goto out;
+		break;
+#endif
 	default:
 		hw_dbg(hw, "Flow control param set incorrectly\n");
 		ret_val = -IXGBE_ERR_CONFIG;
···
 	ixgbe_link_speed speed;
 	bool link_up;
 
+#ifdef CONFIG_DCB
+	if (hw->fc.requested_mode == ixgbe_fc_pfc) {
+		hw->fc.current_mode = hw->fc.requested_mode;
+		goto out;
+	}
+
+#endif
 	/* Validate the packetbuf configuration */
 	if (packetbuf_num < 0 || packetbuf_num > 7) {
 		hw_dbg(hw, "Invalid packet buffer number [%d], expected range "

drivers/net/ixgbe/ixgbe_dcb_82598.c

···
 	reg = IXGBE_READ_REG(hw, IXGBE_RMCS);
 	reg &= ~IXGBE_RMCS_TFCE_802_3X;
 	/* correct the reporting of our flow control status */
-	hw->fc.current_mode = ixgbe_fc_none;
 	reg |= IXGBE_RMCS_TFCE_PRIORITY;
 	IXGBE_WRITE_REG(hw, IXGBE_RMCS, reg);
 

drivers/net/ixgbe/ixgbe_dcb_82599.c

···
 		goto out;
 	}
 
-	/* PFC is mutually exclusive with link flow control */
-	hw->fc.current_mode = ixgbe_fc_none;
-
 	/* Configure PFC Tx thresholds per TC */
 	for (i = 0; i < MAX_TRAFFIC_CLASS; i++) {
 		/* Config and remember Tx */

drivers/net/ixgbe/ixgbe_dcb_nl.c

···
 		adapter->tx_ring = NULL;
 		adapter->rx_ring = NULL;
 
+		adapter->hw.fc.requested_mode = ixgbe_fc_pfc;
 		adapter->flags &= ~IXGBE_FLAG_RSS_ENABLED;
 		adapter->flags |= IXGBE_FLAG_DCB_ENABLED;
 		ixgbe_init_interrupt_scheme(adapter);
···
 	} else {
 		/* Turn off DCB */
 		if (adapter->flags & IXGBE_FLAG_DCB_ENABLED) {
+			adapter->hw.fc.requested_mode = ixgbe_fc_default;
 			if (netif_running(netdev))
 				netdev->netdev_ops->ndo_stop(netdev);
 			ixgbe_reset_interrupt_capability(adapter);

drivers/net/ixgbe/ixgbe_type.h

···
 	ixgbe_fc_rx_pause,
 	ixgbe_fc_tx_pause,
 	ixgbe_fc_full,
+#ifdef CONFIG_DCB
+	ixgbe_fc_pfc,
+#endif
 	ixgbe_fc_default
 };