[PATCH] e100: Render e100 NAPI state machine

Render e100 NAPI state machine to be similar to the non-NAPI one.

Signed-off-by: Mallikarjuna R Chilakala <mallikarjuna.chilakala@intel.com>
Signed-off-by: Ganesh Venkatesan <ganesh.venkatesan@intel.com>
Signed-off-by: John Ronciak <john.ronciak@intel.com>

1 files changed, 71 insertions, 15 deletions

diff --git a/drivers/net/e100.c b/drivers/net/e100.c
index 0f2837ebaab8..2c8c14ebf205 100644
--- a/drivers/net/e100.c
+++ b/drivers/net/e100.c
@@ -269,6 +269,12 @@ enum scb_status {
         rus_mask         = 0x3C,
 };
 
+enum ru_state  {
+        RU_SUSPENDED = 0,
+        RU_RUNNING       = 1,
+        RU_UNINITIALIZED = -1,
+};
+
 enum scb_stat_ack {
         stat_ack_not_ours    = 0x00,
         stat_ack_sw_gen      = 0x04,
@@ -510,7 +516,7 @@ struct nic {
         struct rx *rx_to_use;
         struct rx *rx_to_clean;
         struct rfd blank_rfd;
-        int ru_running;
+        enum ru_state ru_running;
 
         spinlock_t cb_lock                      ____cacheline_aligned;
         spinlock_t cmd_lock;
@@ -1204,7 +1210,9 @@ static void e100_update_stats(struct nic *nic)
                 }
         }
 
-        e100_exec_cmd(nic, cuc_dump_reset, 0);
+        
+        if(e100_exec_cmd(nic, cuc_dump_reset, 0))
+                DPRINTK(TX_ERR, DEBUG, "exec cuc_dump_reset failed\n");
 }
 
 static void e100_adjust_adaptive_ifs(struct nic *nic, int speed, int duplex)
@@ -1298,7 +1306,8 @@ static int e100_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
                 /* SW workaround for ICH[x] 10Mbps/half duplex Tx hang.
                    Issue a NOP command followed by a 1us delay before
                    issuing the Tx command. */
-                e100_exec_cmd(nic, cuc_nop, 0);
+                if(e100_exec_cmd(nic, cuc_nop, 0))
+                        DPRINTK(TX_ERR, DEBUG, "exec cuc_nop failed\n");
                 udelay(1);
         }
 
@@ -1416,12 +1425,18 @@ static int e100_alloc_cbs(struct nic *nic)
         return 0;
 }
 
-static inline void e100_start_receiver(struct nic *nic)
+static inline void e100_start_receiver(struct nic *nic, struct rx *rx)
 {
+        if(!nic->rxs) return;
+        if(RU_SUSPENDED != nic->ru_running) return;
+
+        /* handle init time starts */
+        if(!rx) rx = nic->rxs;
+
         /* (Re)start RU if suspended or idle and RFA is non-NULL */
-        if(!nic->ru_running && nic->rx_to_clean->skb) {
-                e100_exec_cmd(nic, ruc_start, nic->rx_to_clean->dma_addr);
-                nic->ru_running = 1;
+        if(rx->skb) {
+                e100_exec_cmd(nic, ruc_start, rx->dma_addr);
+                nic->ru_running = RU_RUNNING;
         }
 }
 
@@ -1438,6 +1453,13 @@ static inline int e100_rx_alloc_skb(struct nic *nic, struct rx *rx)
         rx->dma_addr = pci_map_single(nic->pdev, rx->skb->data,
                 RFD_BUF_LEN, PCI_DMA_BIDIRECTIONAL);
 
+        if(pci_dma_mapping_error(rx->dma_addr)) {
+                dev_kfree_skb_any(rx->skb);
+                rx->skb = 0;
+                rx->dma_addr = 0;
+                return -ENOMEM;
+        }
+
         /* Link the RFD to end of RFA by linking previous RFD to
          * this one, and clearing EL bit of previous.  */
         if(rx->prev->skb) {
@@ -1472,7 +1494,7 @@ static inline int e100_rx_indicate(struct nic *nic, struct rx *rx,
 
         /* If data isn't ready, nothing to indicate */
         if(unlikely(!(rfd_status & cb_complete)))
-                return -EAGAIN;
+                return -ENODATA;
 
         /* Get actual data size */
         actual_size = le16_to_cpu(rfd->actual_size) & 0x3FFF;
@@ -1483,6 +1505,10 @@ static inline int e100_rx_indicate(struct nic *nic, struct rx *rx,
         pci_unmap_single(nic->pdev, rx->dma_addr,
                 RFD_BUF_LEN, PCI_DMA_FROMDEVICE);
 
+        /* this allows for a fast restart without re-enabling interrupts */
+        if(le16_to_cpu(rfd->command) & cb_el)
+                nic->ru_running = RU_SUSPENDED;
+
         /* Pull off the RFD and put the actual data (minus eth hdr) */
         skb_reserve(skb, sizeof(struct rfd));
         skb_put(skb, actual_size);
@@ -1515,20 +1541,45 @@ static inline void e100_rx_clean(struct nic *nic, unsigned int *work_done,
         unsigned int work_to_do)
 {
         struct rx *rx;
+        int restart_required = 0;
+        struct rx *rx_to_start = NULL;
+
+        /* are we already rnr? then pay attention!!! this ensures that
+         * the state machine progression never allows a start with a 
+         * partially cleaned list, avoiding a race between hardware
+         * and rx_to_clean when in NAPI mode */
+        if(RU_SUSPENDED == nic->ru_running)
+                restart_required = 1;
 
         /* Indicate newly arrived packets */
         for(rx = nic->rx_to_clean; rx->skb; rx = nic->rx_to_clean = rx->next) {
-                if(e100_rx_indicate(nic, rx, work_done, work_to_do))
+                int err = e100_rx_indicate(nic, rx, work_done, work_to_do);
+                if(-EAGAIN == err) {
+                        /* hit quota so have more work to do, restart once
+                         * cleanup is complete */
+                        restart_required = 0;
+                        break;
+                } else if(-ENODATA == err)
                         break; /* No more to clean */
         }
 
+        /* save our starting point as the place we'll restart the receiver */
+        if(restart_required)
+                rx_to_start = nic->rx_to_clean;
+
         /* Alloc new skbs to refill list */
         for(rx = nic->rx_to_use; !rx->skb; rx = nic->rx_to_use = rx->next) {
                 if(unlikely(e100_rx_alloc_skb(nic, rx)))
                         break; /* Better luck next time (see watchdog) */
         }
 
-        e100_start_receiver(nic);
+        if(restart_required) {
+                // ack the rnr?
+                writeb(stat_ack_rnr, &nic->csr->scb.stat_ack);
+                e100_start_receiver(nic, rx_to_start);
+                if(work_done)
+                        (*work_done)++;
+        }
 }
 
 static void e100_rx_clean_list(struct nic *nic)
@@ -1536,6 +1587,8 @@ static void e100_rx_clean_list(struct nic *nic)
         struct rx *rx;
         unsigned int i, count = nic->params.rfds.count;
 
+        nic->ru_running = RU_UNINITIALIZED;
+
         if(nic->rxs) {
                 for(rx = nic->rxs, i = 0; i < count; rx++, i++) {
                         if(rx->skb) {
@@ -1549,7 +1602,6 @@ static void e100_rx_clean_list(struct nic *nic)
         }
 
         nic->rx_to_use = nic->rx_to_clean = NULL;
-        nic->ru_running = 0;
 }
 
 static int e100_rx_alloc_list(struct nic *nic)
@@ -1558,6 +1610,7 @@ static int e100_rx_alloc_list(struct nic *nic)
         unsigned int i, count = nic->params.rfds.count;
 
         nic->rx_to_use = nic->rx_to_clean = NULL;
+        nic->ru_running = RU_UNINITIALIZED;
 
         if(!(nic->rxs = kmalloc(sizeof(struct rx) * count, GFP_ATOMIC)))
                 return -ENOMEM;
@@ -1573,6 +1626,7 @@ static int e100_rx_alloc_list(struct nic *nic)
         }
 
         nic->rx_to_use = nic->rx_to_clean = nic->rxs;
+        nic->ru_running = RU_SUSPENDED;
 
         return 0;
 }
@@ -1594,7 +1648,7 @@ static irqreturn_t e100_intr(int irq, void *dev_id, struct pt_regs *regs)
 
         /* We hit Receive No Resource (RNR); restart RU after cleaning */
         if(stat_ack & stat_ack_rnr)
-                nic->ru_running = 0;
+                nic->ru_running = RU_SUSPENDED;
 
         e100_disable_irq(nic);
         netif_rx_schedule(netdev);
@@ -1684,7 +1738,7 @@ static int e100_up(struct nic *nic)
         if((err = e100_hw_init(nic)))
                 goto err_clean_cbs;
         e100_set_multicast_list(nic->netdev);
-        e100_start_receiver(nic);
+        e100_start_receiver(nic, 0);
         mod_timer(&nic->watchdog, jiffies);
         if((err = request_irq(nic->pdev->irq, e100_intr, SA_SHIRQ,
                 nic->netdev->name, nic->netdev)))
@@ -1759,7 +1813,7 @@ static int e100_loopback_test(struct nic *nic, enum loopback loopback_mode)
                 mdio_write(nic->netdev, nic->mii.phy_id, MII_BMCR,
                         BMCR_LOOPBACK);
 
-        e100_start_receiver(nic);
+        e100_start_receiver(nic, 0);
 
         if(!(skb = dev_alloc_skb(ETH_DATA_LEN))) {
                 err = -ENOMEM;
@@ -2233,6 +2287,7 @@ static int __devinit e100_probe(struct pci_dev *pdev,
 
         e100_get_defaults(nic);
 
+        /* locks must be initialized before calling hw_reset */
         spin_lock_init(&nic->cb_lock);
         spin_lock_init(&nic->cmd_lock);
 
@@ -2348,7 +2403,8 @@ static int e100_resume(struct pci_dev *pdev)
 
         pci_set_power_state(pdev, PCI_D0);
         pci_restore_state(pdev);
-        e100_hw_init(nic);
+        if(e100_hw_init(nic))
+                DPRINTK(HW, ERR, "e100_hw_init failed\n");
 
         netif_device_attach(netdev);
         if(netif_running(netdev))