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From:   Giulio Benetti <giulio.benetti@micronovasrl.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Jiri Slaby <jslaby@suse.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Kees Cook <keescook@chromium.org>,
        Matthias Brugger <mbrugger@suse.com>,
        Allen Pais <allen.lkml@gmail.com>, Sean Young <sean@mess.org>,
        Ed Blake <ed.blake@sondrel.com>,
        Stefan Potyra <Stefan.Potyra@elektrobit.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Joshua Scott <joshua.scott@alliedtelesis.co.nz>,
        Vignesh R <vigneshr@ti.com>,
        Rolf Evers-Fischer <rolf.evers.fischer@aptiv.com>,
        Aaron Sierra <asierra@xes-inc.com>,
        Rafael Gago <rafael.gago@gmail.com>,
        Joel Stanley <joel@jms.id.au>,
        Sean Wang <sean.wang@mediatek.com>,
        linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
        Giulio Benetti <giulio.benetti@micronovasrl.com>
Subject: [PATCH 8/8] serial: core: Mask mctrl with TIOCM_RTS too if rs485 on and RTS_AFTER_SEND set.
Date:   Fri,  1 Jun 2018 14:40:21 +0200
Message-Id: <20180601124021.102970-9-giulio.benetti@micronovasrl.com>
In-Reply-To: <20180601124021.102970-1-giulio.benetti@micronovasrl.com>
References: <20180601124021.102970-1-giulio.benetti@micronovasrl.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

If rs485 is enabled and RTS_AFTER_SEND is set on startup need to keep
TIOCM_RTS asserted to keep rs485 transceiver in RX when idle.

Check if rs485 is on and RTS_AFTER_SEND is set and mask port->mctrl with
TIOCM_RTS too and not only TIOCM_DTR.

Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
---
 drivers/tty/serial/serial_core.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 0466f9f08a91..06d9441f6d20 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2288,6 +2288,16 @@ uart_configure_port(struct uart_driver *drv, struct uart_state *state,
 
 	if (port->type != PORT_UNKNOWN) {
 		unsigned long flags;
+		int rs485_on = port->rs485_config &&
+			(port->rs485.flags & SER_RS485_ENABLED);
+		int RTS_after_send = !!(port->rs485.flags &
+				SER_RS485_RTS_AFTER_SEND);
+		int mctrl;
+
+		if (rs485_on && RTS_after_send)
+			mctrl = port->mctrl & (TIOCM_DTR | TIOCM_RTS);
+		else
+			mctrl = port->mctrl & TIOCM_DTR;
 
 		uart_report_port(drv, port);
 
@@ -2300,7 +2310,7 @@ uart_configure_port(struct uart_driver *drv, struct uart_state *state,
 		 * We probably don't need a spinlock around this, but
 		 */
 		spin_lock_irqsave(&port->lock, flags);
-		port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
+		port->ops->set_mctrl(port, mctrl);
 		spin_unlock_irqrestore(&port->lock, flags);
 
 		/*
-- 
2.17.0