1 files changed, 38 insertions, 12 deletions

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index b69393f2817d..e42eb1e5a21a 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -298,21 +298,22 @@ static void serial_omap_enable_ms(struct uart_port *port)
 static void serial_omap_stop_tx(struct uart_port *port)
 {
         struct uart_omap_port *up = to_uart_omap_port(port);
-        struct circ_buf *xmit = &up->port.state->xmit;
         int res;
 
         pm_runtime_get_sync(up->dev);
 
-        /* handle rs485 */
+        /* Handle RS-485 */
         if (up->rs485.flags & SER_RS485_ENABLED) {
-                /* do nothing if current tx not yet completed */
-                res = serial_in(up, UART_LSR) & UART_LSR_TEMT;
-                if (!res)
-                        return;
-
-                /* if there's no more data to send, turn off rts */
-                if (uart_circ_empty(xmit)) {
-                        /* if rts not already disabled */
+                if (up->scr & OMAP_UART_SCR_TX_EMPTY) {
+                        /* THR interrupt is fired when both TX FIFO and TX
+                         * shift register are empty. This means there's nothing
+                         * left to transmit now, so make sure the THR interrupt
+                         * is fired when TX FIFO is below the trigger level,
+                         * disable THR interrupts and toggle the RS-485 GPIO
+                         * data direction pin if needed.
+                         */
+                        up->scr &= ~OMAP_UART_SCR_TX_EMPTY;
+                        serial_out(up, UART_OMAP_SCR, up->scr);
                         res = (up->rs485.flags & SER_RS485_RTS_AFTER_SEND) ? 1 : 0;
                         if (gpio_get_value(up->rts_gpio) != res) {
                                 if (up->rs485.delay_rts_after_send > 0) {
@@ -320,6 +321,18 @@ static void serial_omap_stop_tx(struct uart_port *port)
                                 }
                                 gpio_set_value(up->rts_gpio, res);
                         }
+                } else {
+                        /* We're asked to stop, but there's still stuff in the
+                         * UART FIFO, so make sure the THR interrupt is fired
+                         * when both TX FIFO and TX shift register are empty.
+                         * The next THR interrupt (if no transmission is started
+                         * in the meantime) will indicate the end of a
+                         * transmission. Therefore we _don't_ disable THR
+                         * interrupts in this situation.
+                         */
+                        up->scr |= OMAP_UART_SCR_TX_EMPTY;
+                        serial_out(up, UART_OMAP_SCR, up->scr);
+                        return;
                 }
         }
 
@@ -399,8 +412,12 @@ static void serial_omap_start_tx(struct uart_port *port)
 
         pm_runtime_get_sync(up->dev);
 
-        /* handle rs485 */
+        /* Handle RS-485 */
         if (up->rs485.flags & SER_RS485_ENABLED) {
+                /* Fire THR interrupts when FIFO is below trigger level */
+                up->scr &= ~OMAP_UART_SCR_TX_EMPTY;
+                serial_out(up, UART_OMAP_SCR, up->scr);
+
                 /* if rts not already enabled */
                 res = (up->rs485.flags & SER_RS485_RTS_ON_SEND) ? 1 : 0;
                 if (gpio_get_value(up->rts_gpio) != res) {
@@ -969,7 +986,7 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
          */
 
         /* Set receive FIFO threshold to 16 characters and
-         * transmit FIFO threshold to 16 spaces
+         * transmit FIFO threshold to 32 spaces
          */
         up->fcr &= ~OMAP_UART_FCR_RX_FIFO_TRIG_MASK;
         up->fcr &= ~OMAP_UART_FCR_TX_FIFO_TRIG_MASK;
@@ -1375,6 +1392,15 @@ serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
         up->ier = mode;
         serial_out(up, UART_IER, up->ier);
 
+        /* If RS-485 is disabled, make sure the THR interrupt is fired when
+         * TX FIFO is below the trigger level.
+         */
+        if (!(up->rs485.flags & SER_RS485_ENABLED) &&
+            (up->scr & OMAP_UART_SCR_TX_EMPTY)) {
+                up->scr &= ~OMAP_UART_SCR_TX_EMPTY;
+                serial_out(up, UART_OMAP_SCR, up->scr);
+        }
+
         spin_unlock_irqrestore(&up->port.lock, flags);
         pm_runtime_mark_last_busy(up->dev);
         pm_runtime_put_autosuspend(up->dev);