amd-xgbe: Add support for the skb->xmit_more flag

Add support to delay telling the hardware about data that is ready to
be transmitted if the skb->xmit_more flag 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-desc.c b/drivers/net/ethernet/amd/xgbe/xgbe-desc.c
index 62cb4d3388dfcb241c4f721e4dfd8186431e5af1..51b68d1299feb957ed5f544446d367a78afa57e7 100644 (file)
--- a/drivers/net/ethernet/amd/xgbe/xgbe-desc.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-desc.c
@@ -378,7 +378,7 @@ static void xgbe_wrapper_tx_descriptor_init(struct xgbe_prv_data *pdata)
 
                ring->cur = 0;
                ring->dirty = 0;
-               ring->tx.queue_stopped = 0;
+               memset(&ring->tx, 0, sizeof(ring->tx));
 
                hw_if->tx_desc_init(channel);
        }
@@ -422,8 +422,7 @@ static void xgbe_wrapper_rx_descriptor_init(struct xgbe_prv_data *pdata)
 
                ring->cur = 0;
                ring->dirty = 0;
-               ring->rx.realloc_index = 0;
-               ring->rx.realloc_threshold = 0;
+               memset(&ring->rx, 0, sizeof(ring->rx));
 
                hw_if->rx_desc_init(channel);
        }

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
index b3d2433b52bb668fe85f5592af8accb437b09994..53f5f66ec2ee43fe5533697860f70d49a458b919 100644 (file)
--- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
@@ -1325,6 +1325,29 @@ static void xgbe_config_dcb_pfc(struct xgbe_prv_data *pdata)
        xgbe_config_flow_control(pdata);
 }
 
+static void xgbe_tx_start_xmit(struct xgbe_channel *channel,
+                              struct xgbe_ring *ring)
+{
+       struct xgbe_prv_data *pdata = channel->pdata;
+       struct xgbe_ring_data *rdata;
+
+       /* Issue a poll command to Tx DMA by writing address
+        * of next immediate free descriptor */
+       rdata = XGBE_GET_DESC_DATA(ring, ring->cur);
+       XGMAC_DMA_IOWRITE(channel, DMA_CH_TDTR_LO,
+                         lower_32_bits(rdata->rdesc_dma));
+
+       /* Start the Tx coalescing timer */
+       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),
+                             HRTIMER_MODE_REL);
+       }
+
+       ring->tx.xmit_more = 0;
+}
+
 static void xgbe_dev_xmit(struct xgbe_channel *channel)
 {
        struct xgbe_prv_data *pdata = channel->pdata;
@@ -1528,20 +1551,13 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
        /* Make sure ownership is written to the descriptor */
        wmb();
 
-       /* Issue a poll command to Tx DMA by writing address
-        * of next immediate free descriptor */
        ring->cur++;
-       rdata = XGBE_GET_DESC_DATA(ring, ring->cur);
-       XGMAC_DMA_IOWRITE(channel, DMA_CH_TDTR_LO,
-                         lower_32_bits(rdata->rdesc_dma));
-
-       /* Start the Tx coalescing timer */
-       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),
-                             HRTIMER_MODE_REL);
-       }
+       if (!packet->skb->xmit_more ||
+           netif_xmit_stopped(netdev_get_tx_queue(pdata->netdev,
+                                                  channel->queue_index)))
+               xgbe_tx_start_xmit(channel, ring);
+       else
+               ring->tx.xmit_more = 1;
 
        DBGPR("  %s: descriptors %u to %u written\n",
              channel->name, start_index & (ring->rdesc_count - 1),
@@ -2802,6 +2818,7 @@ void xgbe_init_function_ptrs_dev(struct xgbe_hw_if *hw_if)
        hw_if->rx_desc_reset = xgbe_rx_desc_reset;
        hw_if->is_last_desc = xgbe_is_last_desc;
        hw_if->is_context_desc = xgbe_is_context_desc;
+       hw_if->tx_start_xmit = xgbe_tx_start_xmit;
 
        /* For FLOW ctrl */
        hw_if->config_tx_flow_control = xgbe_config_tx_flow_control;

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index f9635281c7df8d819b8b980cf83fb98403db303e..02c104dc2aa4294b3730570252ef3cbb0b4ae6ff 100644 (file)
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -225,6 +225,28 @@ static inline unsigned int xgbe_tx_avail_desc(struct xgbe_ring *ring)
        return (ring->rdesc_count - (ring->cur - ring->dirty));
 }
 
+static int xgbe_maybe_stop_tx_queue(struct xgbe_channel *channel,
+                                   struct xgbe_ring *ring, unsigned int count)
+{
+       struct xgbe_prv_data *pdata = channel->pdata;
+
+       if (count > xgbe_tx_avail_desc(ring)) {
+               DBGPR("  Tx queue stopped, not enough descriptors available\n");
+               netif_stop_subqueue(pdata->netdev, channel->queue_index);
+               ring->tx.queue_stopped = 1;
+
+               /* If we haven't notified the hardware because of xmit_more
+                * support, tell it now
+                */
+               if (ring->tx.xmit_more)
+                       pdata->hw_if.tx_start_xmit(channel, ring);
+
+               return NETDEV_TX_BUSY;
+       }
+
+       return 0;
+}
+
 static int xgbe_calc_rx_buf_size(struct net_device *netdev, unsigned int mtu)
 {
        unsigned int rx_buf_size;
@@ -1199,6 +1221,8 @@ static void xgbe_packet_info(struct xgbe_prv_data *pdata,
        unsigned int len;
        unsigned int i;
 
+       packet->skb = skb;
+
        context_desc = 0;
        packet->rdesc_count = 0;
 
@@ -1447,13 +1471,9 @@ static int xgbe_xmit(struct sk_buff *skb, struct net_device *netdev)
        xgbe_packet_info(pdata, ring, skb, packet);
 
        /* Check that there are enough descriptors available */
-       if (packet->rdesc_count > xgbe_tx_avail_desc(ring)) {
-               DBGPR("  Tx queue stopped, not enough descriptors available\n");
-               netif_stop_subqueue(netdev, channel->queue_index);
-               ring->tx.queue_stopped = 1;
-               ret = NETDEV_TX_BUSY;
+       ret = xgbe_maybe_stop_tx_queue(channel, ring, packet->rdesc_count);
+       if (ret)
                goto tx_netdev_return;
-       }
 
        ret = xgbe_prep_tso(skb, packet);
        if (ret) {
@@ -1480,6 +1500,11 @@ static int xgbe_xmit(struct sk_buff *skb, struct net_device *netdev)
        xgbe_print_pkt(netdev, skb, true);
 #endif
 
+       /* Stop the queue in advance if there may not be enough descriptors */
+       xgbe_maybe_stop_tx_queue(channel, ring, XGBE_TX_MAX_DESCS);
+
+       ret = NETDEV_TX_OK;
+
 tx_netdev_return:
        spin_unlock_irqrestore(&ring->lock, flags);
 

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe.h b/drivers/net/ethernet/amd/xgbe/xgbe.h
index ec0d37a917ae51217113839b98b049b2062ab567..eb3387398c6f398e9a836bb0025a61b3df10d42b 100644 (file)
--- a/drivers/net/ethernet/amd/xgbe/xgbe.h
+++ b/drivers/net/ethernet/amd/xgbe/xgbe.h
@@ -140,6 +140,17 @@
 
 #define XGBE_TX_MAX_BUF_SIZE   (0x3fff & ~(64 - 1))
 
+/* Descriptors required for maximum contigous TSO/GSO packet */
+#define XGBE_TX_MAX_SPLIT      ((GSO_MAX_SIZE / XGBE_TX_MAX_BUF_SIZE) + 1)
+
+/* Maximum possible descriptors needed for an SKB:
+ * - Maximum number of SKB frags
+ * - Maximum descriptors for contiguous TSO/GSO packet
+ * - Possible context descriptor
+ * - Possible TSO header descriptor
+ */
+#define XGBE_TX_MAX_DESCS      (MAX_SKB_FRAGS + XGBE_TX_MAX_SPLIT + 2)
+
 #define XGBE_RX_MIN_BUF_SIZE   (ETH_FRAME_LEN + ETH_FCS_LEN + VLAN_HLEN)
 #define XGBE_RX_BUF_ALIGN      64
 #define XGBE_SKB_ALLOC_SIZE    256
@@ -225,6 +236,8 @@
 struct xgbe_prv_data;
 
 struct xgbe_packet_data {
+       struct sk_buff *skb;
+
        unsigned int attributes;
 
        unsigned int errors;
@@ -360,6 +373,7 @@ struct xgbe_ring {
        union {
                struct {
                        unsigned int queue_stopped;
+                       unsigned int xmit_more;
                        unsigned short cur_mss;
                        unsigned short cur_vlan_ctag;
                } tx;
@@ -523,6 +537,7 @@ struct xgbe_hw_if {
        void (*tx_desc_reset)(struct xgbe_ring_data *);
        int (*is_last_desc)(struct xgbe_ring_desc *);
        int (*is_context_desc)(struct xgbe_ring_desc *);
+       void (*tx_start_xmit)(struct xgbe_channel *, struct xgbe_ring *);
 
        /* For FLOW ctrl */
        int (*config_tx_flow_control)(struct xgbe_prv_data *);