via-velocity: Implement NAPI support

This patch adds NAPI support for VIA velocity. The new velocity_poll
function also pairs tx/rx handling twice which improves perforamance on
some workloads (e.g., netperf UDP_STREAM) significantly (that part is
from the VIA driver).

Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 49 insertions, 35 deletions

diff --git a/drivers/net/via-velocity.c b/drivers/net/via-velocity.c
index 7c362b242704..47b28821589b 100644
--- a/drivers/net/via-velocity.c
+++ b/drivers/net/via-velocity.c
@@ -354,12 +354,6 @@ VELOCITY_PARAM(ValPktLen, "Receiving or Drop invalid 802.3 frame");
 */
 VELOCITY_PARAM(wol_opts, "Wake On Lan options");
 
-#define INT_WORKS_DEF   20
-#define INT_WORKS_MIN   10
-#define INT_WORKS_MAX   64
-
-VELOCITY_PARAM(int_works, "Number of packets per interrupt services");
-
 static int rx_copybreak = 200;
 module_param(rx_copybreak, int, 0644);
 MODULE_PARM_DESC(rx_copybreak, "Copy breakpoint for copy-only-tiny-frames");
@@ -503,7 +497,6 @@ static void __devinit velocity_get_options(struct velocity_opt *opts, int index,
         velocity_set_bool_opt(&opts->flags, ValPktLen[index], VAL_PKT_LEN_DEF, VELOCITY_FLAGS_VAL_PKT_LEN, "ValPktLen", devname);
         velocity_set_int_opt((int *) &opts->spd_dpx, speed_duplex[index], MED_LNK_MIN, MED_LNK_MAX, MED_LNK_DEF, "Media link mode", devname);
         velocity_set_int_opt((int *) &opts->wol_opts, wol_opts[index], WOL_OPT_MIN, WOL_OPT_MAX, WOL_OPT_DEF, "Wake On Lan options", devname);
-        velocity_set_int_opt((int *) &opts->int_works, int_works[index], INT_WORKS_MIN, INT_WORKS_MAX, INT_WORKS_DEF, "Interrupt service works", devname);
         opts->numrx = (opts->numrx & ~3);
 }
 
@@ -2109,13 +2102,14 @@ static int velocity_receive_frame(struct velocity_info *vptr, int idx)
  *      any received packets from the receive queue. Hand the ring
  *      slots back to the adapter for reuse.
  */
-static int velocity_rx_srv(struct velocity_info *vptr, int status)
+static int velocity_rx_srv(struct velocity_info *vptr, int status,
+                int budget_left)
 {
         struct net_device_stats *stats = &vptr->dev->stats;
         int rd_curr = vptr->rx.curr;
         int works = 0;
 
-        do {
+        while (works < budget_left) {
                 struct rx_desc *rd = vptr->rx.ring + rd_curr;
 
                 if (!vptr->rx.info[rd_curr].skb)
@@ -2146,7 +2140,8 @@ static int velocity_rx_srv(struct velocity_info *vptr, int status)
                 rd_curr++;
                 if (rd_curr >= vptr->options.numrx)
                         rd_curr = 0;
-        } while (++works <= 15);
+                works++;
+        }
 
         vptr->rx.curr = rd_curr;
 
@@ -2157,6 +2152,40 @@ static int velocity_rx_srv(struct velocity_info *vptr, int status)
         return works;
 }
 
+static int velocity_poll(struct napi_struct *napi, int budget)
+{
+        struct velocity_info *vptr = container_of(napi,
+                        struct velocity_info, napi);
+        unsigned int rx_done;
+        u32 isr_status;
+
+        spin_lock(&vptr->lock);
+        isr_status = mac_read_isr(vptr->mac_regs);
+
+        /* Ack the interrupt */
+        mac_write_isr(vptr->mac_regs, isr_status);
+        if (isr_status & (~(ISR_PRXI | ISR_PPRXI | ISR_PTXI | ISR_PPTXI)))
+                velocity_error(vptr, isr_status);
+
+        /*
+         * Do rx and tx twice for performance (taken from the VIA
+         * out-of-tree driver).
+         */
+        rx_done = velocity_rx_srv(vptr, isr_status, budget / 2);
+        velocity_tx_srv(vptr, isr_status);
+        rx_done += velocity_rx_srv(vptr, isr_status, budget - rx_done);
+        velocity_tx_srv(vptr, isr_status);
+
+        spin_unlock(&vptr->lock);
+
+        /* If budget not fully consumed, exit the polling mode */
+        if (rx_done < budget) {
+                napi_complete(napi);
+                mac_enable_int(vptr->mac_regs);
+        }
+
+        return rx_done;
+}
 
 /**
  *      velocity_intr           -       interrupt callback
@@ -2173,8 +2202,6 @@ static irqreturn_t velocity_intr(int irq, void *dev_instance)
         struct net_device *dev = dev_instance;
         struct velocity_info *vptr = netdev_priv(dev);
         u32 isr_status;
-        int max_count = 0;
-
 
         spin_lock(&vptr->lock);
         isr_status = mac_read_isr(vptr->mac_regs);
@@ -2185,32 +2212,13 @@ static irqreturn_t velocity_intr(int irq, void *dev_instance)
                 return IRQ_NONE;
         }
 
-        mac_disable_int(vptr->mac_regs);
-
-        /*
-         *      Keep processing the ISR until we have completed
-         *      processing and the isr_status becomes zero
-         */
-
-        while (isr_status != 0) {
-                mac_write_isr(vptr->mac_regs, isr_status);
-                if (isr_status & (~(ISR_PRXI | ISR_PPRXI | ISR_PTXI | ISR_PPTXI)))
-                        velocity_error(vptr, isr_status);
-                if (isr_status & (ISR_PRXI | ISR_PPRXI))
-                        max_count += velocity_rx_srv(vptr, isr_status);
-                if (isr_status & (ISR_PTXI | ISR_PPTXI))
-                        max_count += velocity_tx_srv(vptr, isr_status);
-                isr_status = mac_read_isr(vptr->mac_regs);
-                if (max_count > vptr->options.int_works) {
-                        printk(KERN_WARNING "%s: excessive work at interrupt.\n",
-                                dev->name);
-                        max_count = 0;
-                }
+        if (likely(napi_schedule_prep(&vptr->napi))) {
+                mac_disable_int(vptr->mac_regs);
+                __napi_schedule(&vptr->napi);
         }
         spin_unlock(&vptr->lock);
-        mac_enable_int(vptr->mac_regs);
-        return IRQ_HANDLED;
 
+        return IRQ_HANDLED;
 }
 
 /**
@@ -2250,6 +2258,7 @@ static int velocity_open(struct net_device *dev)
 
         mac_enable_int(vptr->mac_regs);
         netif_start_queue(dev);
+        napi_enable(&vptr->napi);
         vptr->flags |= VELOCITY_FLAGS_OPENED;
 out:
         return ret;
@@ -2485,6 +2494,7 @@ static int velocity_close(struct net_device *dev)
 {
         struct velocity_info *vptr = netdev_priv(dev);
 
+        napi_disable(&vptr->napi);
         netif_stop_queue(dev);
         velocity_shutdown(vptr);
 
@@ -2803,6 +2813,7 @@ static int __devinit velocity_found1(struct pci_dev *pdev, const struct pci_devi
         dev->irq = pdev->irq;
         dev->netdev_ops = &velocity_netdev_ops;
         dev->ethtool_ops = &velocity_ethtool_ops;
+        netif_napi_add(dev, &vptr->napi, velocity_poll, VELOCITY_NAPI_WEIGHT);
 
         dev->features |= NETIF_F_HW_VLAN_TX | NETIF_F_HW_VLAN_FILTER |
                 NETIF_F_HW_VLAN_RX;
diff --git a/drivers/net/via-velocity.h b/drivers/net/via-velocity.h
index 499da64773ee..d37a30329312 100644
--- a/drivers/net/via-velocity.h
+++ b/drivers/net/via-velocity.h
@@ -32,6 +32,7 @@
 #define VELOCITY_VERSION       "1.14"
 
 #define VELOCITY_IO_SIZE        256
+#define VELOCITY_NAPI_WEIGHT    64
 
 #define PKT_BUF_SZ          1540
 
@@ -1562,6 +1563,8 @@ struct velocity_info {
         u32 ticks;
 
         u8 rev_id;
+
+        struct napi_struct napi;
 };
 
 /**