diff --git a/drivers/serial/sh-sci.c b/drivers/serial/sh-sci.c
index cd52dd64edf0..304a877d083d 100644
--- a/drivers/serial/sh-sci.c
+++ b/drivers/serial/sh-sci.c
@@ -106,6 +106,7 @@ struct sci_port {
 	struct work_struct		work_tx;
 	struct work_struct		work_rx;
 	struct timer_list		rx_timer;
+	unsigned int			rx_timeout;
 #endif
 };
 
@@ -673,22 +674,22 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
 	struct sci_port *s = to_sci_port(port);
 
 	if (s->chan_rx) {
-		unsigned long tout;
 		u16 scr = sci_in(port, SCSCR);
 		u16 ssr = sci_in(port, SCxSR);
 
 		/* Disable future Rx interrupts */
-		sci_out(port, SCSCR, scr & ~SCI_CTRL_FLAGS_RIE);
+		if (port->type == PORT_SCIFA) {
+			disable_irq_nosync(irq);
+			scr |= 0x4000;
+		} else {
+			scr &= ~SCI_CTRL_FLAGS_RIE;
+		}
+		sci_out(port, SCSCR, scr);
 		/* Clear current interrupt */
 		sci_out(port, SCxSR, ssr & ~(1 | SCxSR_RDxF(port)));
-		/* Calculate delay for 1.5 DMA buffers */
-		tout = (port->timeout - HZ / 50) * s->buf_len_rx * 3 /
-			port->fifosize / 2;
-		dev_dbg(port->dev, "Rx IRQ: setup timeout in %lu ms\n",
-			tout * 1000 / HZ);
-		if (tout < 2)
-			tout = 2;
-		mod_timer(&s->rx_timer, jiffies + tout);
+		dev_dbg(port->dev, "Rx IRQ %lu: setup t-out in %u jiffies\n",
+			jiffies, s->rx_timeout);
+		mod_timer(&s->rx_timer, jiffies + s->rx_timeout);
 
 		return IRQ_HANDLED;
 	}
@@ -925,13 +926,17 @@ static void sci_dma_tx_complete(void *arg)
 	s->cookie_tx = -EINVAL;
 	s->desc_tx = NULL;
 
-	spin_unlock_irqrestore(&port->lock, flags);
-
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_chars_pending(xmit))
+	if (!uart_circ_empty(xmit)) {
 		schedule_work(&s->work_tx);
+	} else if (port->type == PORT_SCIFA) {
+		u16 ctrl = sci_in(port, SCSCR);
+		sci_out(port, SCSCR, ctrl & ~SCI_CTRL_FLAGS_TIE);
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 /* Locking: called with port lock held */
@@ -975,13 +980,13 @@ static void sci_dma_rx_complete(void *arg)
 	unsigned long flags;
 	int count;
 
-	dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
+	dev_dbg(port->dev, "%s(%d) active #%d\n", __func__, port->line, s->active_rx);
 
 	spin_lock_irqsave(&port->lock, flags);
 
 	count = sci_dma_rx_push(s, tty, s->buf_len_rx);
 
-	mod_timer(&s->rx_timer, jiffies + msecs_to_jiffies(5));
+	mod_timer(&s->rx_timer, jiffies + s->rx_timeout);
 
 	spin_unlock_irqrestore(&port->lock, flags);
 
@@ -1053,6 +1058,8 @@ static void sci_submit_rx(struct sci_port *s)
 			sci_rx_dma_release(s, true);
 			return;
 		}
+		dev_dbg(s->port.dev, "%s(): cookie %d to #%d\n", __func__,
+			s->cookie_rx[i], i);
 	}
 
 	s->active_rx = s->cookie_rx[0];
@@ -1110,10 +1117,10 @@ static void work_fn_rx(struct work_struct *work)
 		return;
 	}
 
-	dev_dbg(port->dev, "%s: cookie %d #%d\n", __func__,
-		s->cookie_rx[new], new);
-
 	s->active_rx = s->cookie_rx[!new];
+
+	dev_dbg(port->dev, "%s: cookie %d #%d, new active #%d\n", __func__,
+		s->cookie_rx[new], new, s->active_rx);
 }
 
 static void work_fn_tx(struct work_struct *work)
@@ -1175,23 +1182,28 @@ static void work_fn_tx(struct work_struct *work)
 
 static void sci_start_tx(struct uart_port *port)
 {
+	struct sci_port *s = to_sci_port(port);
 	unsigned short ctrl;
 
 #ifdef CONFIG_SERIAL_SH_SCI_DMA
-	struct sci_port *s = to_sci_port(port);
-
-	if (s->chan_tx) {
-		if (!uart_circ_empty(&s->port.state->xmit) && s->cookie_tx < 0)
-			schedule_work(&s->work_tx);
-
-		return;
+	if (port->type == PORT_SCIFA) {
+		u16 new, scr = sci_in(port, SCSCR);
+		if (s->chan_tx)
+			new = scr | 0x8000;
+		else
+			new = scr & ~0x8000;
+		if (new != scr)
+			sci_out(port, SCSCR, new);
 	}
+	if (s->chan_tx && !uart_circ_empty(&s->port.state->xmit) &&
+	    s->cookie_tx < 0)
+		schedule_work(&s->work_tx);
 #endif
-
-	/* Set TIE (Transmit Interrupt Enable) bit in SCSCR */
-	ctrl = sci_in(port, SCSCR);
-	ctrl |= SCI_CTRL_FLAGS_TIE;
-	sci_out(port, SCSCR, ctrl);
+	if (!s->chan_tx || port->type == PORT_SCIFA) {
+		/* Set TIE (Transmit Interrupt Enable) bit in SCSCR */
+		ctrl = sci_in(port, SCSCR);
+		sci_out(port, SCSCR, ctrl | SCI_CTRL_FLAGS_TIE);
+	}
 }
 
 static void sci_stop_tx(struct uart_port *port)
@@ -1200,6 +1212,8 @@ static void sci_stop_tx(struct uart_port *port)
 
 	/* Clear TIE (Transmit Interrupt Enable) bit in SCSCR */
 	ctrl = sci_in(port, SCSCR);
+	if (port->type == PORT_SCIFA)
+		ctrl &= ~0x8000;
 	ctrl &= ~SCI_CTRL_FLAGS_TIE;
 	sci_out(port, SCSCR, ctrl);
 }
@@ -1210,6 +1224,8 @@ static void sci_start_rx(struct uart_port *port)
 
 	/* Set RIE (Receive Interrupt Enable) bit in SCSCR */
 	ctrl |= sci_in(port, SCSCR);
+	if (port->type == PORT_SCIFA)
+		ctrl &= ~0x4000;
 	sci_out(port, SCSCR, ctrl);
 }
 
@@ -1219,6 +1235,8 @@ static void sci_stop_rx(struct uart_port *port)
 
 	/* Clear RIE (Receive Interrupt Enable) bit in SCSCR */
 	ctrl = sci_in(port, SCSCR);
+	if (port->type == PORT_SCIFA)
+		ctrl &= ~0x4000;
 	ctrl &= ~(SCI_CTRL_FLAGS_RIE | SCI_CTRL_FLAGS_REIE);
 	sci_out(port, SCSCR, ctrl);
 }
@@ -1253,8 +1271,12 @@ static void rx_timer_fn(unsigned long arg)
 {
 	struct sci_port *s = (struct sci_port *)arg;
 	struct uart_port *port = &s->port;
-
 	u16 scr = sci_in(port, SCSCR);
+
+	if (port->type == PORT_SCIFA) {
+		scr &= ~0x4000;
+		enable_irq(s->irqs[1]);
+	}
 	sci_out(port, SCSCR, scr | SCI_CTRL_FLAGS_RIE);
 	dev_dbg(port->dev, "DMA Rx timed out\n");
 	schedule_work(&s->work_rx);
@@ -1404,8 +1426,12 @@ static void sci_shutdown(struct uart_port *port)
 static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 			    struct ktermios *old)
 {
+#ifdef CONFIG_SERIAL_SH_SCI_DMA
+	struct sci_port *s = to_sci_port(port);
+#endif
 	unsigned int status, baud, smr_val, max_baud;
 	int t = -1;
+	u16 scfcr = 0;
 
 	/*
 	 * earlyprintk comes here early on with port->uartclk set to zero.
@@ -1428,7 +1454,7 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 	sci_out(port, SCSCR, 0x00);	/* TE=0, RE=0, CKE1=0 */
 
 	if (port->type != PORT_SCI)
-		sci_out(port, SCFCR, SCFCR_RFRST | SCFCR_TFRST);
+		sci_out(port, SCFCR, scfcr | SCFCR_RFRST | SCFCR_TFRST);
 
 	smr_val = sci_in(port, SCSMR) & 3;
 	if ((termios->c_cflag & CSIZE) == CS7)
@@ -1459,10 +1485,32 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 	}
 
 	sci_init_pins(port, termios->c_cflag);
-	sci_out(port, SCFCR, (termios->c_cflag & CRTSCTS) ? SCFCR_MCE : 0);
+	sci_out(port, SCFCR, scfcr | ((termios->c_cflag & CRTSCTS) ? SCFCR_MCE : 0));
 
 	sci_out(port, SCSCR, SCSCR_INIT(port));
 
+#ifdef CONFIG_SERIAL_SH_SCI_DMA
+	/*
+	 * Calculate delay for 1.5 DMA buffers: see
+	 * drivers/serial/serial_core.c::uart_update_timeout(). With 10 bits
+	 * (CS8), 250Hz, 115200 baud and 64 bytes FIFO, the above function
+	 * calculates 1 jiffie for the data plus 5 jiffies for the "slop(e)."
+	 * Then below we calculate 3 jiffies (12ms) for 1.5 DMA buffers (3 FIFO
+	 * sizes), but it has been found out experimentally, that this is not
+	 * enough: the driver too often needlessly runs on a DMA timeout. 20ms
+	 * as a minimum seem to work perfectly.
+	 */
+	if (s->chan_rx) {
+		s->rx_timeout = (port->timeout - HZ / 50) * s->buf_len_rx * 3 /
+			port->fifosize / 2;
+		dev_dbg(port->dev,
+			"DMA Rx t-out %ums, tty t-out %u jiffies\n",
+			s->rx_timeout * 1000 / HZ, port->timeout);
+		if (s->rx_timeout < msecs_to_jiffies(20))
+			s->rx_timeout = msecs_to_jiffies(20);
+	}
+#endif
+
 	if ((termios->c_cflag & CREAD) != 0)
 		sci_start_rx(port);
 }