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authorAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-04-12 14:51:40 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-04-28 20:07:10 -0700
commit5be605ac9af979265d7b64c160ad9928088a78be (patch)
treea4a156d4f4a1e555751b46890f21236300bd4e78
parentd175feca89a1c162f60f4e3560ca7bc9437c65eb (diff)
tty/serial: atmel: fix hardware handshake selection
Commit 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when hardware handshake is enabled") actually allowed to enable hardware handshaking. Before, the CRTSCTS flags was silently ignored. As the DMA controller can't drive RTS (as explain in the commit message). Ensure that hardware flow control stays disabled when DMA is used and FIFOs are not available. Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> Fixes: 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when hardware handshake is enabled") Cc: stable <stable@vger.kernel.org> # v4.0+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/serial/atmel_serial.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index d9439e6..954941d 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -274,6 +274,13 @@ static bool atmel_use_dma_rx(struct uart_port *port)
return atmel_port->use_dma_rx;
}
+static bool atmel_use_fifo(struct uart_port *port)
+{
+ struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+ return atmel_port->fifo_size;
+}
+
static unsigned int atmel_get_lines_status(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
@@ -2090,7 +2097,12 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
mode |= ATMEL_US_USMODE_RS485;
} else if (termios->c_cflag & CRTSCTS) {
/* RS232 with hardware handshake (RTS/CTS) */
- mode |= ATMEL_US_USMODE_HWHS;
+ if (atmel_use_dma_rx(port) && !atmel_use_fifo(port)) {
+ dev_info(port->dev, "not enabling hardware flow control because DMA is used");
+ termios->c_cflag &= ~CRTSCTS;
+ } else {
+ mode |= ATMEL_US_USMODE_HWHS;
+ }
} else {
/* RS232 without hadware handshake */
mode |= ATMEL_US_USMODE_NORMAL;