serial: sh-sci: Fix late enablement of AUTORTS

When changing hardware control flow for a UART with dedicated RTS/CTS
pins, the new AUTORTS state is not immediately reflected in the
hardware, but only when RTS is raised.  However, the serial core does
not call .set_mctrl() after .set_termios(), hence AUTORTS may only
become effective when the port is closed, and reopened later.
Note that this problem does not happen when manually using stty to
change CRTSCTS, as AUTORTS will work fine on next open.

To fix this, call .set_mctrl() from .set_termios() when dedicated
RTS/CTS pins are present, to refresh the AUTORTS or RTS state.
This is similar to what other drivers supporting AUTORTS do (e.g.
omap-serial).

Reported-by: Baumann, Christoph (C.) <cbaumann@visteon.com>
Fixes: 33f50ffc253854cf ("serial: sh-sci: Fix support for hardware-assisted RTS/CTS")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 446a23bee14008bb5589916f01f3c618d73a2f3f..6e405fb5a23f0b4a38ef65878d5f804c61058526 100644 (file)
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -2372,6 +2372,10 @@ done:
 
                serial_port_out(port, SCFCR, ctrl);
        }
+       if (port->flags & UPF_HARD_FLOW) {
+               /* Refresh (Auto) RTS */
+               sci_set_mctrl(port, port->mctrl);
+       }
 
        scr_val |= SCSCR_RE | SCSCR_TE |
                   (s->cfg->scscr & ~(SCSCR_CKE1 | SCSCR_CKE0));