ixgbe: Properly disable DCB arbiters prior to applying changes

When disabling the Rx and Tx data arbiters prior to configuration changes,
the arbiters were not being shut down properly.  This can create a race
in the DCB hardware blocks, and potentially hang the arbiters.  Also, the
Tx descriptor arbiter shouldn't be disabled when applying configuration
changes; disabling this arbiter can cause a Tx hang.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ixgbe/ixgbe_dcb_82599.c

@@ -145,8 +145,12 @@ s32 ixgbe_dcb_config_rx_arbiter_82599(struct ixgbe_hw *hw,
 	u32    credit_max    = 0;
 	u8     i             = 0;
 
-	/* Disable the arbiter before changing parameters */
-	IXGBE_WRITE_REG(hw, IXGBE_RTRPCS, IXGBE_RTRPCS_ARBDIS);
+	/*
+	 * Disable the arbiter before changing parameters
+	 * (always enable recycle mode; WSP)
+	 */
+	reg = IXGBE_RTRPCS_RRM | IXGBE_RTRPCS_RAC | IXGBE_RTRPCS_ARBDIS;
+	IXGBE_WRITE_REG(hw, IXGBE_RTRPCS, reg);
 
 	/* Map all traffic classes to their UP, 1 to 1 */
 	reg = 0;
@@ -194,9 +198,6 @@ s32 ixgbe_dcb_config_tx_desc_arbiter_82599(struct ixgbe_hw *hw,
 	u32    reg, max_credits;
 	u8     i;
 
-	/* Disable the arbiter before changing parameters */
-	IXGBE_WRITE_REG(hw, IXGBE_RTTDCS, IXGBE_RTTDCS_ARBDIS);
-
 	/* Clear the per-Tx queue credits; we use per-TC instead */
 	for (i = 0; i < 128; i++) {
 		IXGBE_WRITE_REG(hw, IXGBE_RTTDQSEL, i);
@@ -244,8 +245,14 @@ s32 ixgbe_dcb_config_tx_data_arbiter_82599(struct ixgbe_hw *hw,
 	u32 reg;
 	u8 i;
 
-	/* Disable the arbiter before changing parameters */
-	IXGBE_WRITE_REG(hw, IXGBE_RTTPCS, IXGBE_RTTPCS_ARBDIS);
+	/*
+	 * Disable the arbiter before changing parameters
+	 * (always enable recycle mode; SP; arb delay)
+	 */
+	reg = IXGBE_RTTPCS_TPPAC | IXGBE_RTTPCS_TPRM |
+	      (IXGBE_RTTPCS_ARBD_DCB << IXGBE_RTTPCS_ARBD_SHIFT) |
+	      IXGBE_RTTPCS_ARBDIS;
+	IXGBE_WRITE_REG(hw, IXGBE_RTTPCS, reg);
 
 	/* Map all traffic classes to their UP, 1 to 1 */
 	reg = 0;