ucc_geth: NAPI-related bug fixes

Based partly on the gianfar driver, this patch fixes several
bugs which were causing NAPI to be completely unusable.
* An IRQ is still needed in NAPI, to kick off NAPI task,
  and for Tx processing.  Request the IRQ.
* If rx_work_limit = 0 we are not complete.
* While running Rx NAPI processing we must mask Rx events,
  including Rx busy.
* ucc_geth_rx function does not need a lock.
  Could lead to deadlock in NAPI case.
* There's no need to loop reading ucce multiple times in the ISR,
  so while adding the call to schedule NAPI which was not there,
  simplify the event processing into if-else format.
* Rx Busy now kicks off NAPI processing, while still
  being counted as an error.

Signed-off-by: Michael Reiss <michael.f.reiss@freescale.com>
Signed-off-by: Michael Barkowski <michael.barkowski@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

2 files changed, 61 insertions, 40 deletions

diff --git a/drivers/net/ucc_geth.c b/drivers/net/ucc_geth.c
index d93cfde663e9..60be1e775380 100644
--- a/drivers/net/ucc_geth.c
+++ b/drivers/net/ucc_geth.c
@@ -3416,7 +3416,6 @@ static int ucc_geth_rx(struct ucc_geth_private *ugeth, u8 rxQ, int rx_work_limit
 
         ugeth_vdbg("%s: IN", __FUNCTION__);
 
-        spin_lock(&ugeth->lock);
         /* collect received buffers */
         bd = ugeth->rxBd[rxQ];
 
@@ -3464,7 +3463,6 @@ static int ucc_geth_rx(struct ucc_geth_private *ugeth, u8 rxQ, int rx_work_limit
                 skb = get_new_skb(ugeth, bd);
                 if (!skb) {
                         ugeth_warn("%s: No Rx Data Buffer", __FUNCTION__);
-                        spin_unlock(&ugeth->lock);
                         ugeth->stats.rx_dropped++;
                         break;
                 }
@@ -3485,7 +3483,6 @@ static int ucc_geth_rx(struct ucc_geth_private *ugeth, u8 rxQ, int rx_work_limit
         }
 
         ugeth->rxBd[rxQ] = bd;
-        spin_unlock(&ugeth->lock);
         return howmany;
 }
 
@@ -3537,23 +3534,38 @@ static int ucc_geth_tx(struct net_device *dev, u8 txQ)
 static int ucc_geth_poll(struct net_device *dev, int *budget)
 {
         struct ucc_geth_private *ugeth = netdev_priv(dev);
+        struct ucc_geth_info *ug_info;
+        struct ucc_fast_private *uccf;
         int howmany;
-        int rx_work_limit = *budget;
-        u8 rxQ = 0;
+        u8 i;
+        int rx_work_limit;
+        register u32 uccm;
 
+        ug_info = ugeth->ug_info;
+
+        rx_work_limit = *budget;
         if (rx_work_limit > dev->quota)
                 rx_work_limit = dev->quota;
 
-        howmany = ucc_geth_rx(ugeth, rxQ, rx_work_limit);
+        howmany = 0;
+
+        for (i = 0; i < ug_info->numQueuesRx; i++) {
+                howmany += ucc_geth_rx(ugeth, i, rx_work_limit);
+        }
 
         dev->quota -= howmany;
         rx_work_limit -= howmany;
         *budget -= howmany;
 
-        if (rx_work_limit >= 0)
+        if (rx_work_limit > 0) {
                 netif_rx_complete(dev);
+                uccf = ugeth->uccf;
+                uccm = in_be32(uccf->p_uccm);
+                uccm |= UCCE_RX_EVENTS;
+                out_be32(uccf->p_uccm, uccm);
+        }
 
-        return (rx_work_limit < 0) ? 1 : 0;
+        return (rx_work_limit > 0) ? 0 : 1;
 }
 #endif                          /* CONFIG_UGETH_NAPI */
 
@@ -3563,10 +3575,13 @@ static irqreturn_t ucc_geth_irq_handler(int irq, void *info)
         struct ucc_geth_private *ugeth = netdev_priv(dev);
         struct ucc_fast_private *uccf;
         struct ucc_geth_info *ug_info;
-        register u32 ucce = 0;
-        register u32 bit_mask = UCCE_RXBF_SINGLE_MASK;
-        register u32 tx_mask = UCCE_TXBF_SINGLE_MASK;
-        register u8 i;
+        register u32 ucce;
+        register u32 uccm;
+#ifndef CONFIG_UGETH_NAPI
+        register u32 rx_mask;
+#endif
+        register u32 tx_mask;
+        u8 i;
 
         ugeth_vdbg("%s: IN", __FUNCTION__);
 
@@ -3576,48 +3591,53 @@ static irqreturn_t ucc_geth_irq_handler(int irq, void *info)
         uccf = ugeth->uccf;
         ug_info = ugeth->ug_info;
 
-        do {
-                ucce |= (u32) (in_be32(uccf->p_ucce) & in_be32(uccf->p_uccm));
-
-                /* clear event bits for next time */
-                /* Side effect here is to mask ucce variable
-                for future processing below. */
-                out_be32(uccf->p_ucce, ucce);   /* Clear with ones,
-                                                but only bits in UCCM */
-
-                /* We ignore Tx interrupts because Tx confirmation is
-                done inside Tx routine */
+        /* read and clear events */
+        ucce = (u32) in_be32(uccf->p_ucce);
+        uccm = (u32) in_be32(uccf->p_uccm);
+        ucce &= uccm;
+        out_be32(uccf->p_ucce, ucce);
 
+        /* check for receive events that require processing */
+        if (ucce & UCCE_RX_EVENTS) {
+#ifdef CONFIG_UGETH_NAPI
+                if (netif_rx_schedule_prep(dev)) {
+                uccm &= ~UCCE_RX_EVENTS;
+                        out_be32(uccf->p_uccm, uccm);
+                        __netif_rx_schedule(dev);
+                }
+#else
+                rx_mask = UCCE_RXBF_SINGLE_MASK;
                 for (i = 0; i < ug_info->numQueuesRx; i++) {
-                        if (ucce & bit_mask)
-                                ucc_geth_rx(ugeth, i,
-                                            (int)ugeth->ug_info->
-                                            bdRingLenRx[i]);
-                        ucce &= ~bit_mask;
-                        bit_mask <<= 1;
+                        if (ucce & rx_mask)
+                                ucc_geth_rx(ugeth, i, (int)ugeth->ug_info->bdRingLenRx[i]);
+                        ucce &= ~rx_mask;
+                        rx_mask <<= 1;
                 }
+#endif /* CONFIG_UGETH_NAPI */
+        }
 
+        /* Tx event processing */
+        if (ucce & UCCE_TX_EVENTS) {
+                spin_lock(&ugeth->lock);
+                tx_mask = UCCE_TXBF_SINGLE_MASK;
                 for (i = 0; i < ug_info->numQueuesTx; i++) {
                         if (ucce & tx_mask)
                                 ucc_geth_tx(dev, i);
                         ucce &= ~tx_mask;
                         tx_mask <<= 1;
                 }
+                spin_unlock(&ugeth->lock);
+        }
 
-                /* Exceptions */
+        /* Errors and other events */
+        if (ucce & UCCE_OTHER) {
                 if (ucce & UCCE_BSY) {
-                        ugeth_vdbg("Got BUSY irq!!!!");
                         ugeth->stats.rx_errors++;
-                        ucce &= ~UCCE_BSY;
                 }
-                if (ucce & UCCE_OTHER) {
-                        ugeth_vdbg("Got frame with error (ucce - 0x%08x)!!!!",
-                                   ucce);
-                        ugeth->stats.rx_errors++;
-                        ucce &= ~ucce;
+                if (ucce & UCCE_TXE) {
+                        ugeth->stats.tx_errors++;
                 }
         }
-        while (ucce);
 
         return IRQ_HANDLED;
 }
@@ -3677,7 +3697,6 @@ static int ucc_geth_open(struct net_device *dev)
 
         phy_start(ugeth->phydev);
 
-#ifndef CONFIG_UGETH_NAPI
         err =
             request_irq(ugeth->ug_info->uf_info.irq, ucc_geth_irq_handler, 0,
                         "UCC Geth", dev);
@@ -3687,7 +3706,6 @@ static int ucc_geth_open(struct net_device *dev)
                 ucc_geth_stop(ugeth);
                 return err;
         }
-#endif                          /* CONFIG_UGETH_NAPI */
 
         err = ugeth_enable(ugeth, COMM_DIR_RX_AND_TX);
         if (err) {
diff --git a/drivers/net/ucc_geth.h b/drivers/net/ucc_geth.h
index 6e97c20b92aa..7cf3dbc9fd4c 100644
--- a/drivers/net/ucc_geth.h
+++ b/drivers/net/ucc_geth.h
@@ -205,6 +205,9 @@ struct ucc_geth {
 #define UCCE_OTHER       (UCCE_SCAR | UCCE_GRA  | UCCE_CBPR | UCCE_BSY  |\
                         UCCE_RXC  | UCCE_TXC  | UCCE_TXE)
 
+#define UCCE_RX_EVENTS                                                  (UCCE_RXF | UCCE_BSY)
+#define UCCE_TX_EVENTS                                                  (UCCE_TXB | UCCE_TXE)
+
 /* UCC GETH UPSMR (Protocol Specific Mode Register) */
 #define UPSMR_ECM                               0x04000000      /* Enable CAM
                                                                    Miss or