amd-xgbe: Performance enhancements

This patch provides some general performance enhancements for the
driver:
  - Modify the default coalescing settings (reduce usec, increase frames)
  - Change the AXI burst length to 256 bytes (default was 16 bytes which
    was smaller than a cache line)
  - Change the AXI cache settings to write-back/write-allocate which
    allocate cache entries for received packets during the DMA since the
    packet will be processed soon afterwards
  - Combine ioread/iowrite when disabling both the Tx and Rx interrupts
  - Change to processing the Tx/Rx channels in pairs
  - Only recycle the Rx descriptors when a threshold of dirty descriptors
    is reached

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

1 files changed, 58 insertions, 33 deletions

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index b5fdf66f9a56..344e6b19ec0e 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -156,16 +156,21 @@ static void xgbe_enable_rx_tx_ints(struct xgbe_prv_data *pdata)
 {
         struct xgbe_hw_if *hw_if = &pdata->hw_if;
         struct xgbe_channel *channel;
+        enum xgbe_int int_id;
         unsigned int i;
 
         channel = pdata->channel;
         for (i = 0; i < pdata->channel_count; i++, channel++) {
-                if (channel->tx_ring)
-                        hw_if->enable_int(channel,
-                                          XGMAC_INT_DMA_CH_SR_TI);
-                if (channel->rx_ring)
-                        hw_if->enable_int(channel,
-                                          XGMAC_INT_DMA_CH_SR_RI);
+                if (channel->tx_ring && channel->rx_ring)
+                        int_id = XGMAC_INT_DMA_CH_SR_TI_RI;
+                else if (channel->tx_ring)
+                        int_id = XGMAC_INT_DMA_CH_SR_TI;
+                else if (channel->rx_ring)
+                        int_id = XGMAC_INT_DMA_CH_SR_RI;
+                else
+                        continue;
+
+                hw_if->enable_int(channel, int_id);
         }
 }
 
@@ -173,16 +178,21 @@ static void xgbe_disable_rx_tx_ints(struct xgbe_prv_data *pdata)
 {
         struct xgbe_hw_if *hw_if = &pdata->hw_if;
         struct xgbe_channel *channel;
+        enum xgbe_int int_id;
         unsigned int i;
 
         channel = pdata->channel;
         for (i = 0; i < pdata->channel_count; i++, channel++) {
-                if (channel->tx_ring)
-                        hw_if->disable_int(channel,
-                                           XGMAC_INT_DMA_CH_SR_TI);
-                if (channel->rx_ring)
-                        hw_if->disable_int(channel,
-                                           XGMAC_INT_DMA_CH_SR_RI);
+                if (channel->tx_ring && channel->rx_ring)
+                        int_id = XGMAC_INT_DMA_CH_SR_TI_RI;
+                else if (channel->tx_ring)
+                        int_id = XGMAC_INT_DMA_CH_SR_TI;
+                else if (channel->rx_ring)
+                        int_id = XGMAC_INT_DMA_CH_SR_RI;
+                else
+                        continue;
+
+                hw_if->disable_int(channel, int_id);
         }
 }
 
@@ -1114,6 +1124,22 @@ struct net_device_ops *xgbe_get_netdev_ops(void)
         return (struct net_device_ops *)&xgbe_netdev_ops;
 }
 
+static void xgbe_rx_refresh(struct xgbe_channel *channel)
+{
+        struct xgbe_prv_data *pdata = channel->pdata;
+        struct xgbe_desc_if *desc_if = &pdata->desc_if;
+        struct xgbe_ring *ring = channel->rx_ring;
+        struct xgbe_ring_data *rdata;
+
+        desc_if->realloc_skb(channel);
+
+        /* Update the Rx Tail Pointer Register with address of
+         * the last cleaned entry */
+        rdata = XGBE_GET_DESC_DATA(ring, ring->rx.realloc_index - 1);
+        XGMAC_DMA_IOWRITE(channel, DMA_CH_RDTR_LO,
+                          lower_32_bits(rdata->rdesc_dma));
+}
+
 static int xgbe_tx_poll(struct xgbe_channel *channel)
 {
         struct xgbe_prv_data *pdata = channel->pdata;
@@ -1171,7 +1197,6 @@ static int xgbe_rx_poll(struct xgbe_channel *channel, int budget)
 {
         struct xgbe_prv_data *pdata = channel->pdata;
         struct xgbe_hw_if *hw_if = &pdata->hw_if;
-        struct xgbe_desc_if *desc_if = &pdata->desc_if;
         struct xgbe_ring *ring = channel->rx_ring;
         struct xgbe_ring_data *rdata;
         struct xgbe_packet_data *packet;
@@ -1198,6 +1223,9 @@ static int xgbe_rx_poll(struct xgbe_channel *channel, int budget)
                 cur_len = 0;
 
 read_again:
+                if (ring->dirty > (XGBE_RX_DESC_CNT >> 3))
+                        xgbe_rx_refresh(channel);
+
                 rdata = XGBE_GET_DESC_DATA(ring, ring->cur);
 
                 if (hw_if->dev_read(channel))
@@ -1285,16 +1313,6 @@ read_again:
                 napi_gro_receive(&pdata->napi, skb);
         }
 
-        if (received) {
-                desc_if->realloc_skb(channel);
-
-                /* Update the Rx Tail Pointer Register with address of
-                 * the last cleaned entry */
-                rdata = XGBE_GET_DESC_DATA(ring, ring->rx.realloc_index - 1);
-                XGMAC_DMA_IOWRITE(channel, DMA_CH_RDTR_LO,
-                                  lower_32_bits(rdata->rdesc_dma));
-        }
-
         DBGPR("<--xgbe_rx_poll: received = %d\n", received);
 
         return received;
@@ -1305,21 +1323,28 @@ static int xgbe_poll(struct napi_struct *napi, int budget)
         struct xgbe_prv_data *pdata = container_of(napi, struct xgbe_prv_data,
                                                    napi);
         struct xgbe_channel *channel;
-        int processed;
+        int ring_budget;
+        int processed, last_processed;
         unsigned int i;
 
         DBGPR("-->xgbe_poll: budget=%d\n", budget);
 
-        /* Cleanup Tx ring first */
-        channel = pdata->channel;
-        for (i = 0; i < pdata->channel_count; i++, channel++)
-                xgbe_tx_poll(channel);
-
-        /* Process Rx ring next */
         processed = 0;
-        channel = pdata->channel;
-        for (i = 0; i < pdata->channel_count; i++, channel++)
-                processed += xgbe_rx_poll(channel, budget - processed);
+        ring_budget = budget / pdata->rx_ring_count;
+        do {
+                last_processed = processed;
+
+                channel = pdata->channel;
+                for (i = 0; i < pdata->channel_count; i++, channel++) {
+                        /* Cleanup Tx ring first */
+                        xgbe_tx_poll(channel);
+
+                        /* Process Rx ring next */
+                        if (ring_budget > (budget - processed))
+                                ring_budget = budget - processed;
+                        processed += xgbe_rx_poll(channel, ring_budget);
+                }
+        } while ((processed < budget) && (processed != last_processed));
 
         /* If we processed everything, we are done */
         if (processed < budget) {