Blackfin Serial Driver: Fix bug - Increase buffer tail immediately before starting tx dma.

http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=2920

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

1 files changed, 18 insertions, 14 deletions

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index 69ac7007682e..2fb3081c5022 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -64,15 +64,20 @@ static void bfin_serial_mctrl_check(struct bfin_serial_port *uart);
 static void bfin_serial_stop_tx(struct uart_port *port)
 {
         struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
+        struct circ_buf *xmit = &uart->port.info->xmit;
 #if !defined(CONFIG_BF54x) && !defined(CONFIG_SERIAL_BFIN_DMA)
         unsigned short ier;
 #endif
 
         while (!(UART_GET_LSR(uart) & TEMT))
-                continue;
+                cpu_relax();
 
 #ifdef CONFIG_SERIAL_BFIN_DMA
         disable_dma(uart->tx_dma_channel);
+        xmit->tail = (xmit->tail + uart->tx_count) & (UART_XMIT_SIZE - 1);
+        uart->port.icount.tx += uart->tx_count;
+        uart->tx_count = 0;
+        uart->tx_done = 1;
 #else
 #ifdef CONFIG_BF54x
         /* Clear TFI bit */
@@ -94,7 +99,8 @@ static void bfin_serial_start_tx(struct uart_port *port)
         struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
 
 #ifdef CONFIG_SERIAL_BFIN_DMA
-        bfin_serial_dma_tx_chars(uart);
+        if (uart->tx_done)
+                bfin_serial_dma_tx_chars(uart);
 #else
 #ifdef CONFIG_BF54x
         UART_SET_IER(uart, ETBEI);
@@ -389,12 +395,10 @@ static void bfin_serial_dma_tx_chars(struct bfin_serial_port *uart)
         unsigned short ier;
         int flags = 0;
 
-        if (!uart->tx_done)
-                return;
         uart->tx_done = 0;
 
         if (uart_circ_empty(xmit) || uart_tx_stopped(&uart->port)) {
-                bfin_serial_stop_tx(&uart->port);
+                uart->tx_count = 0;
                 uart->tx_done = 1;
                 return;
         }
@@ -428,9 +432,6 @@ static void bfin_serial_dma_tx_chars(struct bfin_serial_port *uart)
         set_dma_x_modify(uart->tx_dma_channel, 1);
         enable_dma(uart->tx_dma_channel);
 
-        xmit->tail = (xmit->tail + uart->tx_count) & (UART_XMIT_SIZE - 1);
-        uart->port.icount.tx += uart->tx_count;
-
 #ifdef CONFIG_BF54x
         UART_SET_IER(uart, ETBEI);
 #else
@@ -515,8 +516,8 @@ static irqreturn_t bfin_serial_dma_tx_int(int irq, void *dev_id)
 
         spin_lock(&uart->port.lock);
         if (!(get_dma_curr_irqstat(uart->tx_dma_channel)&DMA_RUN)) {
-                clear_dma_irqstat(uart->tx_dma_channel);
                 disable_dma(uart->tx_dma_channel);
+                clear_dma_irqstat(uart->tx_dma_channel);
 #ifdef CONFIG_BF54x
                 UART_CLEAR_IER(uart, ETBEI);
 #else
@@ -527,7 +528,8 @@ static irqreturn_t bfin_serial_dma_tx_int(int irq, void *dev_id)
                 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
                         uart_write_wakeup(&uart->port);
 
-                uart->tx_done = 1;
+                xmit->tail = (xmit->tail + uart->tx_count) & (UART_XMIT_SIZE - 1);
+                uart->port.icount.tx += uart->tx_count;
 
                 bfin_serial_dma_tx_chars(uart);
         }
@@ -542,12 +544,14 @@ static irqreturn_t bfin_serial_dma_rx_int(int irq, void *dev_id)
         unsigned short irqstat;
 
         uart->rx_dma_nrows++;
-        if (uart->rx_dma_nrows == DMA_RX_YCOUNT) {
+        uart->rx_dma_buf.tail = DMA_RX_XCOUNT * uart->rx_dma_nrows;
+        bfin_serial_dma_rx_chars(uart);
+        if (uart->rx_dma_nrows >= DMA_RX_YCOUNT) {
                 uart->rx_dma_nrows = 0;
-                uart->rx_dma_buf.tail = DMA_RX_XCOUNT*DMA_RX_YCOUNT;
-                bfin_serial_dma_rx_chars(uart);
-                uart->rx_dma_buf.head = uart->rx_dma_buf.tail = 0;
+                uart->rx_dma_buf.tail = 0;
         }
+        uart->rx_dma_buf.head = uart->rx_dma_buf.tail;
+
         spin_lock(&uart->port.lock);
         irqstat = get_dma_curr_irqstat(uart->rx_dma_channel);
         clear_dma_irqstat(uart->rx_dma_channel);