On 07/09/2016 at 18:13:23 +0200, Richard Genoud wrote :
> Commit 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when
> hardware handshake is enabled") broke the hardware handshake when GPIOs
> where used.
>
> Hardware handshake with GPIOs used to work before this commit because
> the CRTSCTS flag (termios->c_cflag) was set, but not the
> ATMEL_US_USMODE_HWHS flag (controller register) ; so hardware handshake
> enabled, but not handled by the controller.
>
> This commit restores this behaviour.
>
> NB: -stable is not Cced because it doesn't cleanly apply on 4.1+
> and it will also need previous commit:
> "serial: mctrl_gpio: implement mctrl_gpio_use_rtscts"
>
> Signed-off-by: Richard Genoud <richard.gen...@gmail.com>
> Fixes: 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when hardware
> handshake is enabled")
Acked-by: Alexandre Belloni <alexandre.bell...@free-electrons.com>
> ---
> drivers/tty/serial/atmel_serial.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/atmel_serial.c
> b/drivers/tty/serial/atmel_serial.c
> index 2eaa18ddef61..e9b4fbf88c2d 100644
> --- a/drivers/tty/serial/atmel_serial.c
> +++ b/drivers/tty/serial/atmel_serial.c
> @@ -2025,6 +2025,7 @@ static void atmel_serial_pm(struct uart_port *port,
> unsigned int state,
> static void atmel_set_termios(struct uart_port *port, struct ktermios
> *termios,
> struct ktermios *old)
> {
> + struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> unsigned long flags;
> unsigned int old_mode, mode, imr, quot, baud;
>
> @@ -2126,8 +2127,12 @@ static void atmel_set_termios(struct uart_port *port,
> struct ktermios *termios,
> atmel_uart_writel(port, ATMEL_US_TTGR,
> port->rs485.delay_rts_after_send);
> mode |= ATMEL_US_USMODE_RS485;
> - } else if (termios->c_cflag & CRTSCTS) {
> - /* RS232 with hardware handshake (RTS/CTS) */
> + } else if ((termios->c_cflag & CRTSCTS) &&
> + !mctrl_gpio_use_rtscts(atmel_port->gpios)) {
> + /*
> + * RS232 with hardware handshake (RTS/CTS)
> + * handled by the controller.
> + */
> 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;
> @@ -2135,7 +2140,7 @@ static void atmel_set_termios(struct uart_port *port,
> struct ktermios *termios,
> mode |= ATMEL_US_USMODE_HWHS;
> }
> } else {
> - /* RS232 without hadware handshake */
> + /* RS232 without hadware handshake or controlled by GPIOs */
> mode |= ATMEL_US_USMODE_NORMAL;
> }
>
--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
