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    SubjectRe: [PATCHv2 2/3] tty/serial: at91: fix hardware handshake with GPIOs
    On Mon, Sep 12, 2016 at 11:47:32AM +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.

    s/where/were/

    > 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.genoud@gmail.com>
    > Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
    > Fixes: 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when hardware handshake is enabled")
    > ---
    > 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)) {

    IMHO the behaviour of the hw controlled pins shouldn't change when
    mctrl_gpio is in use (if possible). But I don't understand the issue so
    I guess you need a better changelog.


    > + /*
    > + * 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 */

    When touching this line, please also do s/hadware/hardware/.

    > mode |= ATMEL_US_USMODE_NORMAL;
    > }

    Best regards
    Uwe

    --
    Pengutronix e.K. | Uwe Kleine-König |
    Industrial Linux Solutions | http://www.pengutronix.de/ |

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