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

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

1 files changed, 28 insertions, 25 deletions

diff --git a/drivers/atm/solos-pci.c b/drivers/atm/solos-pci.c
index 5e228a3f7502..e7691b3328f9 100644
--- 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)