This is a note to let you know that I've just added the patch titled tty: serial: atmel: Call dma_async_issue_pending() to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tty-serial-atmel-call-dma_async_issue_pending.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 87a086bbbc194fc91ff8448ce775483fde340587 Author: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx> Date: Thu Nov 25 11:00:18 2021 +0200 tty: serial: atmel: Call dma_async_issue_pending() [ 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> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index da076493b336a..3b2c25bd2e06b 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1007,6 +1007,8 @@ 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) @@ -1273,6 +1275,8 @@ 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: