1 files changed, 30 insertions, 42 deletions

diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 1386625fc4ca..a2e67e6df3a1 100644
--- 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