Stop dmaengine transfer in sci_stop_tx(). Otherwise, the following
message is possible output when system enters suspend and while
transferring data, because clearing TIE bit in SCSCR is not able to
stop any dmaengine transfer.

    sh-sci e6550000.serial: ttySC1: Unable to drain transmitter

Notes:
 - sci_dma_stop_tx() is a macro in the .h file because struct sci_port
   is declared in the .c file and #ifdef should be in the .h file.
 - This patch uses dmaengine_terminate_async() so that we can apply
   this into longterm kernel v4.9.x or later.

Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 Changes from v1:
 - Don't put #ifdef in the .c file.
 - Update the commit description.
 https://lore.kernel.org/linux-renesas-soc/TY2PR01MB3692C545672195370487FA60D83C9@TY2PR01MB3692.jpnprd01.prod.outlook.com/T/#t (local)
 
 drivers/tty/serial/sh-sci.c |  2 ++
 drivers/tty/serial/sh-sci.h | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 4baf1316ea72..3793cf9f352c 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c

@@ -610,6 +610,8 @@ static void sci_stop_tx(struct uart_port *port)
 	ctrl &= ~SCSCR_TIE;
 
 	serial_port_out(port, SCSCR, ctrl);
+
+	sci_dma_stop_tx(port);
 }
 
 static void sci_start_rx(struct uart_port *port)

diff --git a/drivers/tty/serial/sh-sci.h b/drivers/tty/serial/sh-sci.h
index c0dfe4382898..435c674af1ce 100644
--- a/drivers/tty/serial/sh-sci.h
+++ b/drivers/tty/serial/sh-sci.h

@@ -174,3 +174,19 @@ enum {
 	(((port)->type == PORT_SCI) ? SCI_TDxE_CLEAR : SCIF_TDxE_CLEAR)
 #define SCxSR_BREAK_CLEAR(port) \
 	(((port)->type == PORT_SCI) ? SCI_BREAK_CLEAR : SCIF_BREAK_CLEAR)
+
+#ifdef CONFIG_SERIAL_SH_SCI_DMA
+#define sci_dma_stop_tx(port)					\
+{								\
+	struct sci_port *s = to_sci_port(port);			\
+								\
+	if (s->chan_tx && !dma_submit_error(s->cookie_tx)) {	\
+		dmaengine_terminate_async(s->chan_tx);		\
+		s->cookie_tx = -EINVAL;				\
+	}							\
+}
+#else
+static inline void sci_dma_stop_tx(struct uart_port *port)
+{
+}
+#endif /* CONFIG_SERIAL_SH_SCI_DMA */

-- 
2.25.1