[PATCH 5.10 105/563] tty: serial: atmel: Call dma_async_issue_pending()

[Greg Kroah-Hartman]

From: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>

[ Upstream commit 4f4b9b5895614eb2e2b5f4cab7858f44bd113e1b ]

The driver wrongly assummed that tx_submit() will start the transfer,
which is not the case, now that the at_xdmac driver is fixed. tx_submit
is supposed to push the current transaction descriptor to a pending queue,
waiting for issue_pending to be called. issue_pending must start the
transfer, not tx_submit.

Fixes: 34df42f59a60 ("serial: at91: add rx dma support")
Fixes: 08f738be88bb ("serial: at91: add tx dma support")
Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211125090028.786832-4-tudor.ambarus@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/tty/serial/atmel_serial.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 396fe8c51f93b..602065bfc9bb8 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1009,6 +1009,8 @@ static void atmel_tx_dma(struct uart_port *port)
 				atmel_port->cookie_tx);
 			return;
 		}
+
+		dma_async_issue_pending(chan);
 	}
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
@@ -1275,6 +1277,8 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
 		goto chan_err;
 	}
 
+	dma_async_issue_pending(atmel_port->chan_rx);
+
 	return 0;
 
 chan_err:
-- 
2.34.1