ixgbe: Fix interrupt configuration for 82599

The interrupt models using EITR have changed in 82599. The way the register
is laid out, the change is transparent to some of the existing code.
However, some of it isn't. This patch fixes all the cases where EITR
handling is different than 82598.

Signed-off-by: Jesse Brandeburg <[e-mail]>
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.h

···
 };
 
 /* Helper macros to switch between ints/sec and what the register uses.
- * And yes, it's the same math going both ways.
+ * And yes, it's the same math going both ways.  The lowest value
+ * supported by all of the ixgbe hardware is 8.
  */
 #define EITR_INTS_PER_SEC_TO_REG(_eitr) \
-	((_eitr) ? (1000000000 / ((_eitr) * 256)) : 0)
+	((_eitr) ? (1000000000 / ((_eitr) * 256)) : 8)
 #define EITR_REG_TO_INTS_PER_SEC EITR_INTS_PER_SEC_TO_REG
 
 #define IXGBE_DESC_UNUSED(R) \
···
 extern int ixgbe_init_interrupt_scheme(struct ixgbe_adapter *adapter);
 void ixgbe_napi_add_all(struct ixgbe_adapter *adapter);
 void ixgbe_napi_del_all(struct ixgbe_adapter *adapter);
+extern void ixgbe_write_eitr(struct ixgbe_adapter *, int, u32);
 
 #endif /* _IXGBE_H_ */

drivers/net/ixgbe/ixgbe_ethtool.c

···
                               struct ethtool_coalesce *ec)
 {
 	struct ixgbe_adapter *adapter = netdev_priv(netdev);
-	struct ixgbe_hw *hw = &adapter->hw;
 	int i;
 
 	if (ec->tx_max_coalesced_frames_irq)
 		adapter->tx_ring[0].work_limit = ec->tx_max_coalesced_frames_irq;
 
 	if (ec->rx_coalesce_usecs > 1) {
+		/* check the limits */
+		if ((1000000/ec->rx_coalesce_usecs > IXGBE_MAX_INT_RATE) ||
+		    (1000000/ec->rx_coalesce_usecs < IXGBE_MIN_INT_RATE))
+			return -EINVAL;
+
 		/* store the value in ints/second */
 		adapter->eitr_param = 1000000/ec->rx_coalesce_usecs;
 
 		/* static value of interrupt rate */
 		adapter->itr_setting = adapter->eitr_param;
-		/* clear the lower bit */
+		/* clear the lower bit as its used for dynamic state */
 		adapter->itr_setting &= ~1;
 	} else if (ec->rx_coalesce_usecs == 1) {
 		/* 1 means dynamic mode */
 		adapter->eitr_param = 20000;
 		adapter->itr_setting = 1;
 	} else {
-		/* any other value means disable eitr, which is best
-		 * served by setting the interrupt rate very high */
-		adapter->eitr_param = 3000000;
+		/*
+		 * any other value means disable eitr, which is best
+		 * served by setting the interrupt rate very high
+		 */
+		adapter->eitr_param = IXGBE_MAX_INT_RATE;
 		adapter->itr_setting = 0;
 	}
 
 	for (i = 0; i < adapter->num_msix_vectors - NON_Q_VECTORS; i++) {
 		struct ixgbe_q_vector *q_vector = &adapter->q_vector[i];
 		if (q_vector->txr_count && !q_vector->rxr_count)
+			/* tx vector gets half the rate */
 			q_vector->eitr = (adapter->eitr_param >> 1);
 		else
 			/* rx only or mixed */
 			q_vector->eitr = adapter->eitr_param;
-		IXGBE_WRITE_REG(hw, IXGBE_EITR(i),
-		                EITR_INTS_PER_SEC_TO_REG(q_vector->eitr));
+		ixgbe_write_eitr(adapter, i,
+		                 EITR_INTS_PER_SEC_TO_REG(q_vector->eitr));
 	}
 
 	return 0;

drivers/net/ixgbe/ixgbe_main.c

···
 		/* if this is a tx only vector halve the interrupt rate */
 		if (q_vector->txr_count && !q_vector->rxr_count)
 			q_vector->eitr = (adapter->eitr_param >> 1);
-		else
+		else if (q_vector->rxr_count)
 			/* rx only */
 			q_vector->eitr = adapter->eitr_param;
 
+		/*
+		 * since ths is initial set up don't need to call
+		 * ixgbe_write_eitr helper
+		 */
 		IXGBE_WRITE_REG(&adapter->hw, IXGBE_EITR(v_idx),
 		                EITR_INTS_PER_SEC_TO_REG(q_vector->eitr));
 	}
···
 	return retval;
 }
 
+/**
+ * ixgbe_write_eitr - write EITR register in hardware specific way
+ * @adapter: pointer to adapter struct
+ * @v_idx: vector index into q_vector array
+ * @itr_reg: new value to be written in *register* format, not ints/s
+ *
+ * This function is made to be called by ethtool and by the driver
+ * when it needs to update EITR registers at runtime.  Hardware
+ * specific quirks/differences are taken care of here.
+ */
+void ixgbe_write_eitr(struct ixgbe_adapter *adapter, int v_idx, u32 itr_reg)
+{
+	struct ixgbe_hw *hw = &adapter->hw;
+	if (adapter->hw.mac.type == ixgbe_mac_82598EB) {
+		/* must write high and low 16 bits to reset counter */
+		itr_reg |= (itr_reg << 16);
+	} else if (adapter->hw.mac.type == ixgbe_mac_82599EB) {
+		/*
+		 * set the WDIS bit to not clear the timer bits and cause an
+		 * immediate assertion of the interrupt
+		 */
+		itr_reg |= IXGBE_EITR_CNT_WDIS;
+	}
+	IXGBE_WRITE_REG(hw, IXGBE_EITR(v_idx), itr_reg);
+}
+
 static void ixgbe_set_itr_msix(struct ixgbe_q_vector *q_vector)
 {
 	struct ixgbe_adapter *adapter = q_vector->adapter;
-	struct ixgbe_hw *hw = &adapter->hw;
 	u32 new_itr;
 	u8 current_itr, ret_itr;
 	int i, r_idx, v_idx = ((void *)q_vector - (void *)(adapter->q_vector)) /
···
 
 	if (new_itr != q_vector->eitr) {
 		u32 itr_reg;
+
+		/* save the algorithm value here, not the smoothed one */
+		q_vector->eitr = new_itr;
 		/* do an exponential smoothing */
 		new_itr = ((q_vector->eitr * 90)/100) + ((new_itr * 10)/100);
-		q_vector->eitr = new_itr;
 		itr_reg = EITR_INTS_PER_SEC_TO_REG(new_itr);
-		if (adapter->hw.mac.type == ixgbe_mac_82599EB)
-			/* Resolution is 2 usec on 82599, so halve the rate */
-			itr_reg >>= 1;
-		/* must write high and low 16 bits to reset counter */
-		DPRINTK(TX_ERR, DEBUG, "writing eitr(%d): %08X\n", v_idx,
-		        itr_reg);
-		IXGBE_WRITE_REG(hw, IXGBE_EITR(v_idx), itr_reg | (itr_reg)<<16);
+		ixgbe_write_eitr(adapter, v_idx, itr_reg);
 	}
 
 	return;
···
 	/* If all Rx work done, exit the polling mode */
 	if (work_done < budget) {
 		napi_complete(napi);
-		if (adapter->itr_setting & 3)
+		if (adapter->itr_setting & 1)
 			ixgbe_set_itr_msix(q_vector);
 		if (!test_bit(__IXGBE_DOWN, &adapter->state))
 			IXGBE_WRITE_REG(&adapter->hw, IXGBE_EIMS, rx_ring->v_idx);
···
 	/* If all Rx work done, exit the polling mode */
 	if (work_done < budget) {
 		napi_complete(napi);
-		if (adapter->itr_setting & 3)
+		if (adapter->itr_setting & 1)
 			ixgbe_set_itr_msix(q_vector);
 		if (!test_bit(__IXGBE_DOWN, &adapter->state))
 			IXGBE_WRITE_REG(&adapter->hw, IXGBE_EIMS, enable_mask);
···
 
 static void ixgbe_set_itr(struct ixgbe_adapter *adapter)
 {
-	struct ixgbe_hw *hw = &adapter->hw;
 	struct ixgbe_q_vector *q_vector = adapter->q_vector;
 	u8 current_itr;
 	u32 new_itr = q_vector->eitr;
···
 
 	if (new_itr != q_vector->eitr) {
 		u32 itr_reg;
+
+		/* save the algorithm value here, not the smoothed one */
+		q_vector->eitr = new_itr;
 		/* do an exponential smoothing */
 		new_itr = ((q_vector->eitr * 90)/100) + ((new_itr * 10)/100);
-		q_vector->eitr = new_itr;
 		itr_reg = EITR_INTS_PER_SEC_TO_REG(new_itr);
-		if (adapter->hw.mac.type == ixgbe_mac_82599EB)
-			/* Resolution is 2 usec on 82599, so halve the rate */
-			itr_reg >>= 1;
-		/* must write high and low 16 bits to reset counter */
-		IXGBE_WRITE_REG(hw, IXGBE_EITR(0), itr_reg | (itr_reg)<<16);
+		ixgbe_write_eitr(adapter, 0, itr_reg);
 	}
 
 	return;
···
 	                  0xA54F2BEC, 0xEA49AF7C, 0xE214AD3D, 0xB855AABE,
 	                  0x6A3E67EA, 0x14364D17, 0x3BED200D};
 	u32 fctrl, hlreg0;
-	u32 reta = 0, mrqc;
+	u32 reta = 0, mrqc = 0;
 	u32 rdrxctl;
 	int rx_buf_len;
 
···
 	/* If budget not fully consumed, exit the polling mode */
 	if (work_done < budget) {
 		napi_complete(napi);
-		if (adapter->itr_setting & 3)
+		if (adapter->itr_setting & 1)
 			ixgbe_set_itr(adapter);
 		if (!test_bit(__IXGBE_DOWN, &adapter->state))
 			ixgbe_irq_enable(adapter);

drivers/net/ixgbe/ixgbe_type.h

···
 #define IXGBE_EIMS_EX(_i)   (0x00AA0 + (_i) * 4)
 #define IXGBE_EIMC_EX(_i)   (0x00AB0 + (_i) * 4)
 #define IXGBE_EIAM_EX(_i)   (0x00AD0 + (_i) * 4)
+/*
+ * 82598 EITR is 16 bits but set the limits based on the max
+ * supported by all ixgbe hardware.  82599 EITR is only 12 bits,
+ * with the lower 3 always zero.
+ */
+#define IXGBE_MAX_INT_RATE 488281
+#define IXGBE_MIN_INT_RATE 956
+#define IXGBE_MAX_EITR     0x00000FF8
+#define IXGBE_MIN_EITR     8
 #define IXGBE_EITR(_i)  (((_i) <= 23) ? (0x00820 + ((_i) * 4)) : \
                          (0x012300 + (((_i) - 24) * 4)))
-#define IXGBE_EITR_ITR_INT_MASK 0x00000FFF
+#define IXGBE_EITR_ITR_INT_MASK 0x00000FF8
 #define IXGBE_EITR_LLI_MOD      0x00008000
 #define IXGBE_EITR_CNT_WDIS     0x80000000
 #define IXGBE_IVAR(_i)  (0x00900 + ((_i) * 4)) /* 24 at 0x900-0x960 */