synclink_gt: fix transmit race and timeout

[pandora-kernel.git] / drivers / char / synclink_gt.c

diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 1386625..a2e67e6 100644 (file)
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -467,7 +467,6 @@ static unsigned int free_tbuf_count(struct slgt_info *info);
 static unsigned int tbuf_bytes(struct slgt_info *info);
 static void reset_tbufs(struct slgt_info *info);
 static void tdma_reset(struct slgt_info *info);
-static void tdma_start(struct slgt_info *info);
 static void tx_load(struct slgt_info *info, const char *buf, unsigned int count);
 
 static void get_signals(struct slgt_info *info);
@@ -795,6 +794,18 @@ static void set_termios(struct tty_struct *tty, struct ktermios *old_termios)
        }
 }
 
+static void update_tx_timer(struct slgt_info *info)
+{
+       /*
+        * use worst case speed of 1200bps to calculate transmit timeout
+        * based on data in buffers (tbuf_bytes) and FIFO (128 bytes)
+        */
+       if (info->params.mode == MGSL_MODE_HDLC) {
+               int timeout  = (tbuf_bytes(info) * 7) + 1000;
+               mod_timer(&info->tx_timer, jiffies + msecs_to_jiffies(timeout));
+       }
+}
+
 static int write(struct tty_struct *tty,
                 const unsigned char *buf, int count)
 {
@@ -838,8 +849,18 @@ start:
                spin_lock_irqsave(&info->lock,flags);
                if (!info->tx_active)
                        tx_start(info);
-               else
-                       tdma_start(info);
+               else if (!(rd_reg32(info, TDCSR) & BIT0)) {
+                       /* transmit still active but transmit DMA stopped */
+                       unsigned int i = info->tbuf_current;
+                       if (!i)
+                               i = info->tbuf_count;
+                       i--;
+                       /* if DMA buf unsent must try later after tx idle */
+                       if (desc_count(info->tbufs[i]))
+                               ret = 0;
+               }
+               if (ret > 0)
+                       update_tx_timer(info);
                spin_unlock_irqrestore(&info->lock,flags);
        }
 
@@ -1502,10 +1523,9 @@ static int hdlcdev_xmit(struct sk_buff *skb, struct net_device *dev)
        /* save start time for transmit timeout detection */
        dev->trans_start = jiffies;
 
-       /* start hardware transmitter if necessary */
        spin_lock_irqsave(&info->lock,flags);
-       if (!info->tx_active)
-               tx_start(info);
+       tx_start(info);
+       update_tx_timer(info);
        spin_unlock_irqrestore(&info->lock,flags);
 
        return 0;
@@ -3946,50 +3966,19 @@ static void tx_start(struct slgt_info *info)
                        slgt_irq_on(info, IRQ_TXUNDER + IRQ_TXIDLE);
                        /* clear tx idle and underrun status bits */
                        wr_reg16(info, SSR, (unsigned short)(IRQ_TXIDLE + IRQ_TXUNDER));
-                       if (info->params.mode == MGSL_MODE_HDLC)
-                               mod_timer(&info->tx_timer, jiffies +
-                                               msecs_to_jiffies(5000));
                } else {
                        slgt_irq_off(info, IRQ_TXDATA);
                        slgt_irq_on(info, IRQ_TXIDLE);
                        /* clear tx idle status bit */
                        wr_reg16(info, SSR, IRQ_TXIDLE);
                }
-               tdma_start(info);
+               /* set 1st descriptor address and start DMA */
+               wr_reg32(info, TDDAR, info->tbufs[info->tbuf_start].pdesc);
+               wr_reg32(info, TDCSR, BIT2 + BIT0);
                info->tx_active = true;
        }
 }
 
-/*
- * start transmit DMA if inactive and there are unsent buffers
- */
-static void tdma_start(struct slgt_info *info)
-{
-       unsigned int i;
-
-       if (rd_reg32(info, TDCSR) & BIT0)
-               return;
-
-       /* transmit DMA inactive, check for unsent buffers */
-       i = info->tbuf_start;
-       while (!desc_count(info->tbufs[i])) {
-               if (++i == info->tbuf_count)
-                       i = 0;
-               if (i == info->tbuf_current)
-                       return;
-       }
-       info->tbuf_start = i;
-
-       /* there are unsent buffers, start transmit DMA */
-
-       /* reset needed if previous error condition */
-       tdma_reset(info);
-
-       /* set 1st descriptor address */
-       wr_reg32(info, TDDAR, info->tbufs[info->tbuf_start].pdesc);
-       wr_reg32(info, TDCSR, BIT2 + BIT0); /* IRQ + DMA enable */
-}
-
 static void tx_stop(struct slgt_info *info)
 {
        unsigned short val;
@@ -5004,8 +4993,7 @@ static void tx_timeout(unsigned long context)
                info->icount.txtimeout++;
        }
        spin_lock_irqsave(&info->lock,flags);
-       info->tx_active = false;
-       info->tx_count = 0;
+       tx_stop(info);
        spin_unlock_irqrestore(&info->lock,flags);
 
 #if SYNCLINK_GENERIC_HDLC