[PATCH 5.10 079/593] serial: sh-sci: Stop dmaengine transfer in sci_stop_tx()

From: Greg Kroah-Hartman
Date: Mon Jul 12 2021 - 02:39:18 EST

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

commit 08a84410a04f05c7c1b8e833f552416d8eb9f6fe upstream.

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

Note that this driver has already used some #ifdef in the .c file
so that this patch also uses #ifdef to fix the issue. Otherwise,
build errors happens if the CONFIG_SERIAL_SH_SCI_DMA is disabled.

Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.9+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210610110806.277932-1-yoshihiro.shimoda.uh@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/tty/serial/sh-sci.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -610,6 +610,14 @@ static void sci_stop_tx(struct uart_port
ctrl &= ~SCSCR_TIE;

serial_port_out(port, SCSCR, ctrl);
+ if (to_sci_port(port)->chan_tx &&
+ !dma_submit_error(to_sci_port(port)->cookie_tx)) {
+ dmaengine_terminate_async(to_sci_port(port)->chan_tx);
+ to_sci_port(port)->cookie_tx = -EINVAL;
+ }

static void sci_start_rx(struct uart_port *port)