amd-xgbe: Perform Tx coalescing on a packet basis

The current form of Tx coalescing works on a descriptor basis instead
of on a packet basis and doesn't take into account TSO packets. Update
the Tx coalescing support to work on a packet basis, taking into
account the number of packets associated with a TSO transmit. Also,
only activate the Tx timer if a timer value is set.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
index 78db5a6..b3d2433 100644 (file)
--- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
@@ -1334,7 +1334,7 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
        struct xgbe_packet_data *packet = &ring->packet_data;
        unsigned int csum, tso, vlan;
        unsigned int tso_context, vlan_context;
-       unsigned int tx_coalesce, tx_frames;
+       unsigned int tx_set_ic;
        int start_index = ring->cur;
        int i;
 
@@ -1357,10 +1357,26 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
        else
                vlan_context = 0;
 
-       tx_coalesce = (pdata->tx_usecs || pdata->tx_frames) ? 1 : 0;
-       tx_frames = pdata->tx_frames;
-       if (tx_coalesce && !channel->tx_timer_active)
-               ring->coalesce_count = 0;
+       /* Determine if an interrupt should be generated for this Tx:
+        *   Interrupt:
+        *     - Tx frame count exceeds the frame count setting
+        *     - Addition of Tx frame count to the frame count since the
+        *       last interrupt was set exceeds the frame count setting
+        *   No interrupt:
+        *     - No frame count setting specified (ethtool -C ethX tx-frames 0)
+        *     - Addition of Tx frame count to the frame count since the
+        *       last interrupt was set does not exceed the frame count setting
+        */
+       ring->coalesce_count += packet->tx_packets;
+       if (!pdata->tx_frames)
+               tx_set_ic = 0;
+       else if (packet->tx_packets > pdata->tx_frames)
+               tx_set_ic = 1;
+       else if ((ring->coalesce_count % pdata->tx_frames) <
+                packet->tx_packets)
+               tx_set_ic = 1;
+       else
+               tx_set_ic = 0;
 
        rdata = XGBE_GET_DESC_DATA(ring, ring->cur);
        rdesc = rdata->rdesc;
@@ -1427,13 +1443,6 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
        if (XGMAC_GET_BITS(packet->attributes, TX_PACKET_ATTRIBUTES, PTP))
                XGMAC_SET_BITS_LE(rdesc->desc2, TX_NORMAL_DESC2, TTSE, 1);
 
-       /* Set IC bit based on Tx coalescing settings */
-       XGMAC_SET_BITS_LE(rdesc->desc2, TX_NORMAL_DESC2, IC, 1);
-       if (tx_coalesce && (!tx_frames ||
-                           (++ring->coalesce_count % tx_frames)))
-               /* Clear IC bit */
-               XGMAC_SET_BITS_LE(rdesc->desc2, TX_NORMAL_DESC2, IC, 0);
-
        /* Mark it as First Descriptor */
        XGMAC_SET_BITS_LE(rdesc->desc3, TX_NORMAL_DESC3, FD, 1);
 
@@ -1478,13 +1487,6 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
                XGMAC_SET_BITS_LE(rdesc->desc2, TX_NORMAL_DESC2, HL_B1L,
                                  rdata->skb_dma_len);
 
-               /* Set IC bit based on Tx coalescing settings */
-               XGMAC_SET_BITS_LE(rdesc->desc2, TX_NORMAL_DESC2, IC, 1);
-               if (tx_coalesce && (!tx_frames ||
-                                   (++ring->coalesce_count % tx_frames)))
-                       /* Clear IC bit */
-                       XGMAC_SET_BITS_LE(rdesc->desc2, TX_NORMAL_DESC2, IC, 0);
-
                /* Set OWN bit */
                XGMAC_SET_BITS_LE(rdesc->desc3, TX_NORMAL_DESC3, OWN, 1);
 
@@ -1500,6 +1502,10 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
        /* Set LAST bit for the last descriptor */
        XGMAC_SET_BITS_LE(rdesc->desc3, TX_NORMAL_DESC3, LD, 1);
 
+       /* Set IC bit based on Tx coalescing settings */
+       if (tx_set_ic)
+               XGMAC_SET_BITS_LE(rdesc->desc2, TX_NORMAL_DESC2, IC, 1);
+
        /* Save the Tx info to report back during cleanup */
        rdata->tx.packets = packet->tx_packets;
        rdata->tx.bytes = packet->tx_bytes;
@@ -1530,7 +1536,7 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
                          lower_32_bits(rdata->rdesc_dma));
 
        /* Start the Tx coalescing timer */
-       if (tx_coalesce && !channel->tx_timer_active) {
+       if (pdata->tx_usecs && !channel->tx_timer_active) {
                channel->tx_timer_active = 1;
                hrtimer_start(&channel->tx_timer,
                              ktime_set(0, pdata->tx_usecs * NSEC_PER_USEC),