diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 8678f0c8699d7168e67437cb22c13d027f64e5e5..4561ce2fba6d21cb459619114e416816d90ddc6c 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -468,7 +468,7 @@ 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 tx_load(struct slgt_info *info, const char *buf, unsigned int count);
+static bool tx_load(struct slgt_info *info, const char *buf, unsigned int count);
static void get_signals(struct slgt_info *info);
static void set_signals(struct slgt_info *info);
@@ -813,59 +813,32 @@ static int write(struct tty_struct *tty,
int ret = 0;
struct slgt_info *info = tty->driver_data;
unsigned long flags;
- unsigned int bufs_needed;
if (sanity_check(info, tty->name, "write"))
- goto cleanup;
+ return -EIO;
+
DBGINFO(("%s write count=%d\n", info->device_name, count));
- if (!info->tx_buf)
- goto cleanup;
+ if (!info->tx_buf || (count > info->max_frame_size))
+ return -EIO;
- if (count > info->max_frame_size) {
- ret = -EIO;
- goto cleanup;
- }
+ if (!count || tty->stopped || tty->hw_stopped)
+ return 0;
- if (!count)
- goto cleanup;
+ spin_lock_irqsave(&info->lock, flags);
- if (!info->tx_active && info->tx_count) {
+ if (info->tx_count) {
/* send accumulated data from send_char() */
- tx_load(info, info->tx_buf, info->tx_count);
- goto start;
+ if (!tx_load(info, info->tx_buf, info->tx_count))
+ goto cleanup;
+ info->tx_count = 0;
}
- bufs_needed = (count/DMABUFSIZE);
- if (count % DMABUFSIZE)
- ++bufs_needed;
- if (bufs_needed > free_tbuf_count(info))
- goto cleanup;
- ret = info->tx_count = count;
- tx_load(info, buf, count);
- goto start;
-
-start:
- if (info->tx_count && !tty->stopped && !tty->hw_stopped) {
- spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active)
- tx_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);
- }
+ if (tx_load(info, buf, count))
+ ret = count;
cleanup:
+ spin_unlock_irqrestore(&info->lock, flags);
DBGINFO(("%s write rc=%d\n", info->device_name, ret));
return ret;
}
@@ -882,7 +855,7 @@ static int put_char(struct tty_struct *tty, unsigned char ch)
if (!info->tx_buf)
return 0;
spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active && (info->tx_count < info->max_frame_size)) {
+ if (info->tx_count < info->max_frame_size) {
info->tx_buf[info->tx_count++] = ch;
ret = 1;
}
@@ -981,10 +954,8 @@ static void flush_chars(struct tty_struct *tty)
DBGINFO(("%s flush_chars start transmit\n", info->device_name));
spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active && info->tx_count) {
- tx_load(info, info->tx_buf,info->tx_count);
- tx_start(info);
- }
+ if (info->tx_count && tx_load(info, info->tx_buf, info->tx_count))
+ info->tx_count = 0;
spin_unlock_irqrestore(&info->lock,flags);
}
@@ -997,10 +968,9 @@ static void flush_buffer(struct tty_struct *tty)
return;
DBGINFO(("%s flush_buffer\n", info->device_name));
- spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active)
- info->tx_count = 0;
- spin_unlock_irqrestore(&info->lock,flags);
+ spin_lock_irqsave(&info->lock, flags);
+ info->tx_count = 0;
+ spin_unlock_irqrestore(&info->lock, flags);
tty_wakeup(tty);
}
@@ -1033,12 +1003,10 @@ static void tx_release(struct tty_struct *tty)
if (sanity_check(info, tty->name, "tx_release"))
return;
DBGINFO(("%s tx_release\n", info->device_name));
- spin_lock_irqsave(&info->lock,flags);
- if (!info->tx_active && info->tx_count) {
- tx_load(info, info->tx_buf, info->tx_count);
- tx_start(info);
- }
- spin_unlock_irqrestore(&info->lock,flags);
+ spin_lock_irqsave(&info->lock, flags);
+ if (info->tx_count && tx_load(info, info->tx_buf, info->tx_count))
+ info->tx_count = 0;
+ spin_unlock_irqrestore(&info->lock, flags);
}
/*
@@ -1506,27 +1474,25 @@ static netdev_tx_t hdlcdev_xmit(struct sk_buff *skb,
DBGINFO(("%s hdlc_xmit\n", dev->name));
+ if (!skb->len)
+ return NETDEV_TX_OK;
+
/* stop sending until this frame completes */
netif_stop_queue(dev);
- /* copy data to device buffers */
- info->tx_count = skb->len;
- tx_load(info, skb->data, skb->len);
-
/* update network statistics */
dev->stats.tx_packets++;
dev->stats.tx_bytes += skb->len;
- /* done with socket buffer, so free it */
- dev_kfree_skb(skb);
-
/* save start time for transmit timeout detection */
dev->trans_start = jiffies;
- spin_lock_irqsave(&info->lock,flags);
- tx_start(info);
- update_tx_timer(info);
- spin_unlock_irqrestore(&info->lock,flags);
+ spin_lock_irqsave(&info->lock, flags);
+ tx_load(info, skb->data, skb->len);
+ spin_unlock_irqrestore(&info->lock, flags);
+
+ /* done with socket buffer, so free it */
+ dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
@@ -2180,7 +2146,7 @@ static void isr_serial(struct slgt_info *info)
if (info->params.mode == MGSL_MODE_ASYNC) {
if (status & IRQ_TXIDLE) {
- if (info->tx_count)
+ if (info->tx_active)
isr_txeom(info, status);
}
if (info->rx_pio && (status & IRQ_RXDATA))
@@ -2276,13 +2242,42 @@ static void isr_tdma(struct slgt_info *info)
}
}
+/*
+ * return true if there are unsent tx DMA buffers, otherwise false
+ *
+ * if there are unsent buffers then info->tbuf_start
+ * is set to index of first unsent buffer
+ */
+static bool unsent_tbufs(struct slgt_info *info)
+{
+ unsigned int i = info->tbuf_current;
+ bool rc = false;
+
+ /*
+ * search backwards from last loaded buffer (precedes tbuf_current)
+ * for first unsent buffer (desc_count > 0)
+ */
+
+ do {
+ if (i)
+ i--;
+ else
+ i = info->tbuf_count - 1;
+ if (!desc_count(info->tbufs[i]))
+ break;
+ info->tbuf_start = i;
+ rc = true;
+ } while (i != info->tbuf_current);
+
+ return rc;
+}
+
static void isr_txeom(struct slgt_info *info, unsigned short status)
{
DBGISR(("%s txeom status=%04x\n", info->device_name, status));
slgt_irq_off(info, IRQ_TXDATA + IRQ_TXIDLE + IRQ_TXUNDER);
tdma_reset(info);
- reset_tbufs(info);
if (status & IRQ_TXUNDER) {
unsigned short val = rd_reg16(info, TCR);
wr_reg16(info, TCR, (unsigned short)(val | BIT2)); /* set reset bit */
@@ -2297,8 +2292,12 @@ static void isr_txeom(struct slgt_info *info, unsigned short status)
info->icount.txok++;
}
+ if (unsent_tbufs(info)) {
+ tx_start(info);
+ update_tx_timer(info);
+ return;
+ }
info->tx_active = false;
- info->tx_count = 0;
del_timer(&info->tx_timer);
@@ -3949,7 +3948,7 @@ static void tx_start(struct slgt_info *info)
info->tx_enabled = true;
}
- if (info->tx_count) {
+ if (desc_count(info->tbufs[info->tbuf_start])) {
info->drop_rts_on_tx_done = false;
if (info->params.mode != MGSL_MODE_ASYNC) {
@@ -4772,25 +4771,36 @@ static unsigned int tbuf_bytes(struct slgt_info *info)
}
/*
- * load transmit DMA buffer(s) with data
+ * load data into transmit DMA buffer ring and start transmitter if needed
+ * return true if data accepted, otherwise false (buffers full)
*/
-static void tx_load(struct slgt_info *info, const char *buf, unsigned int size)
+static bool tx_load(struct slgt_info *info, const char *buf, unsigned int size)
{
unsigned short count;
unsigned int i;
struct slgt_desc *d;
- if (size == 0)
- return;
+ /* check required buffer space */
+ if (DIV_ROUND_UP(size, DMABUFSIZE) > free_tbuf_count(info))
+ return false;
DBGDATA(info, buf, size, "tx");
+ /*
+ * copy data to one or more DMA buffers in circular ring
+ * tbuf_start = first buffer for this data
+ * tbuf_current = next free buffer
+ *
+ * Copy all data before making data visible to DMA controller by
+ * setting descriptor count of the first buffer.
+ * This prevents an active DMA controller from reading the first DMA
+ * buffers of a frame and stopping before the final buffers are filled.
+ */
+
info->tbuf_start = i = info->tbuf_current;
while (size) {
d = &info->tbufs[i];
- if (++i == info->tbuf_count)
- i = 0;
count = (unsigned short)((size > DMABUFSIZE) ? DMABUFSIZE : size);
memcpy(d->buf, buf, count);
@@ -4808,11 +4818,27 @@ static void tx_load(struct slgt_info *info, const char *buf, unsigned int size)
else
set_desc_eof(*d, 0);
- set_desc_count(*d, count);
+ /* set descriptor count for all but first buffer */
+ if (i != info->tbuf_start)
+ set_desc_count(*d, count);
d->buf_count = count;
+
+ if (++i == info->tbuf_count)
+ i = 0;
}
info->tbuf_current = i;
+
+ /* set first buffer count to make new data visible to DMA controller */
+ d = &info->tbufs[info->tbuf_start];
+ set_desc_count(*d, d->buf_count);
+
+ /* start transmitter if needed and update transmit timeout */
+ if (!info->tx_active)
+ tx_start(info);
+ update_tx_timer(info);
+
+ return true;
}
static int register_test(struct slgt_info *info)
@@ -4934,9 +4960,7 @@ static int loopback_test(struct slgt_info *info)
spin_lock_irqsave(&info->lock,flags);
async_mode(info);
rx_start(info);
- info->tx_count = count;
tx_load(info, buf, count);
- tx_start(info);
spin_unlock_irqrestore(&info->lock, flags);
/* wait for receive complete */