igb: Update RXDCTL/TXDCTL configurations

This change cleans up the RXDCTL and TXDCTL configurations and optimizes RX
performance by allowing back write-backs on all hardware other than 82576.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by:  Aaron Brown  <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

2 files changed, 12 insertions, 16 deletions

diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
index 265e151b66c4..577fd3e797e5 100644
--- a/drivers/net/ethernet/intel/igb/igb.h
+++ b/drivers/net/ethernet/intel/igb/igb.h
@@ -100,11 +100,12 @@ struct vf_data_storage {
  */
 #define IGB_RX_PTHRESH                     8
 #define IGB_RX_HTHRESH                     8
-#define IGB_RX_WTHRESH                     1
 #define IGB_TX_PTHRESH                     8
 #define IGB_TX_HTHRESH                     1
+#define IGB_RX_WTHRESH                     ((hw->mac.type == e1000_82576 && \
+                                             adapter->msix_entries) ? 1 : 4)
 #define IGB_TX_WTHRESH                     ((hw->mac.type == e1000_82576 && \
-                                             adapter->msix_entries) ? 1 : 16)
+                                             adapter->msix_entries) ? 1 : 16)
 
 /* this is the size past which hardware will drop packets when setting LPE=0 */
 #define MAXIMUM_ETHERNET_VLAN_SIZE 1522
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 3cb1bc96bf70..aa78c10a2ec3 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -2666,14 +2666,12 @@ void igb_configure_tx_ring(struct igb_adapter *adapter,
                            struct igb_ring *ring)
 {
         struct e1000_hw *hw = &adapter->hw;
-        u32 txdctl;
+        u32 txdctl = 0;
         u64 tdba = ring->dma;
         int reg_idx = ring->reg_idx;
 
         /* disable the queue */
-        txdctl = rd32(E1000_TXDCTL(reg_idx));
-        wr32(E1000_TXDCTL(reg_idx),
-                        txdctl & ~E1000_TXDCTL_QUEUE_ENABLE);
+        wr32(E1000_TXDCTL(reg_idx), 0);
         wrfl();
         mdelay(10);
 
@@ -2685,7 +2683,7 @@ void igb_configure_tx_ring(struct igb_adapter *adapter,
 
         ring->head = hw->hw_addr + E1000_TDH(reg_idx);
         ring->tail = hw->hw_addr + E1000_TDT(reg_idx);
-        writel(0, ring->head);
+        wr32(E1000_TDH(reg_idx), 0);
         writel(0, ring->tail);
 
         txdctl |= IGB_TX_PTHRESH;
@@ -3028,12 +3026,10 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
         struct e1000_hw *hw = &adapter->hw;
         u64 rdba = ring->dma;
         int reg_idx = ring->reg_idx;
-        u32 srrctl, rxdctl;
+        u32 srrctl = 0, rxdctl = 0;
 
         /* disable the queue */
-        rxdctl = rd32(E1000_RXDCTL(reg_idx));
-        wr32(E1000_RXDCTL(reg_idx),
-                        rxdctl & ~E1000_RXDCTL_QUEUE_ENABLE);
+        wr32(E1000_RXDCTL(reg_idx), 0);
 
         /* Set DMA base address registers */
         wr32(E1000_RDBAL(reg_idx),
@@ -3045,7 +3041,7 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
         /* initialize head and tail */
         ring->head = hw->hw_addr + E1000_RDH(reg_idx);
         ring->tail = hw->hw_addr + E1000_RDT(reg_idx);
-        writel(0, ring->head);
+        wr32(E1000_RDH(reg_idx), 0);
         writel(0, ring->tail);
 
         /* set descriptor configuration */
@@ -3076,13 +3072,12 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
         /* set filtering for VMDQ pools */
         igb_set_vmolr(adapter, reg_idx & 0x7, true);
 
-        /* enable receive descriptor fetching */
-        rxdctl = rd32(E1000_RXDCTL(reg_idx));
-        rxdctl |= E1000_RXDCTL_QUEUE_ENABLE;
-        rxdctl &= 0xFFF00000;
         rxdctl |= IGB_RX_PTHRESH;
         rxdctl |= IGB_RX_HTHRESH << 8;
         rxdctl |= IGB_RX_WTHRESH << 16;
+
+        /* enable receive descriptor fetching */
+        rxdctl |= E1000_RXDCTL_QUEUE_ENABLE;
         wr32(E1000_RXDCTL(reg_idx), rxdctl);
 }