diff mbox

[2/5] serial: 8250: don't change the fifo trigger level when using dma

Message ID 1395755430-346-3-git-send-email-wei.sern.chan@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

wei.sern.chan@intel.com March 25, 2014, 1:50 p.m. UTC 
From: Heikki Krogerus <heikki.krogerus@linux.intel.com>

DMA engines usually expect the fifo trigger level to be
aligned with the burst size. It should not be changed even
with small baud rates. This will fix an issue with
Designware DMA engine where the data can not be transferred
over UART with lower baud rates then 2400.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 2797f6fb6727d8ac5127f88aee1fd059db0be24b)
Signed-off-by: Maurice Petallo <mauricex.r.petallo@intel.com>
---
 drivers/tty/serial/8250/8250_core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox

Patch

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index d28d7af..3d508f3 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -2322,7 +2322,7 @@  serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 
 	if (up->capabilities & UART_CAP_FIFO && port->fifosize > 1) {
 		fcr = uart_config[port->type].fcr;
-		if (baud < 2400 || fifo_bug) {
+		if ((baud < 2400 && !up->dma) || fifo_bug) {
 			fcr &= ~UART_FCR_TRIGGER_MASK;
 			fcr |= UART_FCR_TRIGGER_1;
 		}