Le 12/04/2016 14:51, Alexandre Belloni a écrit :
> 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@xxxxxxxxxxxxxxxxxx>
Yes, I agree with the fix:
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
We can also add the following tags:
Fixes: 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when
hardware handshake is enabled")
Cc: stable <stable@xxxxxxxxxxxxxxx> # v4.0+
Bye,
> ---
> drivers/tty/serial/atmel_serial.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index d9439e6ab719..954941dd8124 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;
>
--
Nicolas Ferre
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