solos: Clean up handling of card->tx_mask a little

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/atm/solos-pci.c b/drivers/atm/solos-pci.c
index 5e228a3..e7691b3 100644 (file)
--- a/drivers/atm/solos-pci.c
+++ b/drivers/atm/solos-pci.c
@@ -140,7 +140,7 @@ module_param(fpga_upgrade, int, 0444);
 
 static void fpga_queue(struct solos_card *card, int port, struct sk_buff *skb,
                       struct atm_vcc *vcc);
-static int fpga_tx(struct solos_card *);
+static uint32_t fpga_tx(struct solos_card *);
 static irqreturn_t solos_irq(int irq, void *dev_id);
 static struct atm_vcc* find_vcc(struct atm_dev *dev, short vpi, int vci);
 static int list_vccs(int vci);
@@ -438,8 +438,6 @@ static int send_command(struct solos_card *card, int dev, const char *buf, size_
        struct sk_buff *skb;
        struct pkt_hdr *header;
 
-//     dev_dbg(&card->dev->dev, "size: %d\n", size);
-
        if (size > (BUF_SIZE - sizeof(*header))) {
                dev_dbg(&card->dev->dev, "Command is too big.  Dropping request\n");
                return 0;
@@ -574,9 +572,9 @@ static irqreturn_t solos_irq(int irq, void *dev_id)
        struct solos_card *card = dev_id;
        int handled = 1;
 
-       //ACK IRQ
        iowrite32(0, card->config_regs + IRQ_CLEAR);
 
+       /* If we're up and running, just kick the tasklet to process TX/RX */
        if (card->atmdev[0])
                tasklet_schedule(&card->tlet);
        else
@@ -588,16 +586,16 @@ static irqreturn_t solos_irq(int irq, void *dev_id)
 void solos_bh(unsigned long card_arg)
 {
        struct solos_card *card = (void *)card_arg;
-       int port;
        uint32_t card_flags;
        uint32_t rx_done = 0;
+       int port;
 
-       card_flags = ioread32(card->config_regs + FLAGS_ADDR);
-
-       /* The TX bits are set if the channel is busy; clear if not. We want to
-          invoke fpga_tx() unless _all_ the bits for active channels are set */
-       if ((card_flags & card->tx_mask) != card->tx_mask)
-               fpga_tx(card);
+       /*
+        * Since fpga_tx() is going to need to read the flags under its lock,
+        * it can return them to us so that we don't have to hit PCI MMIO
+        * again for the same information
+        */
+       card_flags = fpga_tx(card);
 
        for (port = 0; port < card->nr_ports; port++) {
                if (card_flags & (0x10 << port)) {
@@ -892,9 +890,8 @@ static void fpga_queue(struct solos_card *card, int port, struct sk_buff *skb,
        spin_lock_irqsave(&card->tx_queue_lock, flags);
        old_len = skb_queue_len(&card->tx_queue[port]);
        skb_queue_tail(&card->tx_queue[port], skb);
-       if (!old_len) {
+       if (!old_len)
                card->tx_mask |= (1 << port);
-       }
        spin_unlock_irqrestore(&card->tx_queue_lock, flags);
 
        /* Theoretically we could just schedule the tasklet here, but
@@ -903,9 +900,9 @@ static void fpga_queue(struct solos_card *card, int port, struct sk_buff *skb,
                fpga_tx(card);
 }
 
-static int fpga_tx(struct solos_card *card)
+static uint32_t fpga_tx(struct solos_card *card)
 {
-       uint32_t tx_pending;
+       uint32_t tx_pending, card_flags;
        uint32_t tx_started = 0;
        struct sk_buff *skb;
        struct atm_vcc *vcc;
@@ -913,19 +910,24 @@ static int fpga_tx(struct solos_card *card)
        unsigned long flags;
 
        spin_lock_irqsave(&card->tx_lock, flags);
-
-       tx_pending = ioread32(card->config_regs + FLAGS_ADDR) & card->tx_mask;
-
-       dev_vdbg(&card->dev->dev, "TX Flags are %X\n", tx_pending);
-
-       for (port = 0; port < card->nr_ports; port++) {
-               if (card->atmdev[port] && !(tx_pending & (1 << port))) {
+       
+       card_flags = ioread32(card->config_regs + FLAGS_ADDR);
+       /*
+        * The queue lock is required for _writing_ to tx_mask, but we're
+        * OK to read it here without locking. The only potential update
+        * that we could race with is in fpga_queue() where it sets a bit
+        * for a new port... but it's going to call this function again if
+        * it's doing that, anyway.
+        */
+       tx_pending = card->tx_mask & ~card_flags;
+
+       for (port = 0; tx_pending; tx_pending >>= 1, port++) {
+               if (tx_pending & 1) {
                        struct sk_buff *oldskb = card->tx_skb[port];
-
                        if (oldskb)
                                pci_unmap_single(card->dev, SKB_CB(oldskb)->dma_addr,
                                                 oldskb->len, PCI_DMA_TODEVICE);
-                       
+
                        spin_lock(&card->tx_queue_lock);
                        skb = skb_dequeue(&card->tx_queue[port]);
                        if (!skb)
@@ -966,8 +968,9 @@ static int fpga_tx(struct solos_card *card)
        if (tx_started)
                iowrite32(tx_started, card->config_regs + FLAGS_ADDR);
 
+ out:
        spin_unlock_irqrestore(&card->tx_lock, flags);
-       return 0;
+       return card_flags;
 }
 
 static int psend(struct atm_vcc *vcc, struct sk_buff *skb)