From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giulio Benetti Subject: [PATCH 3/4] serial: 8250: Make em485_rts_after_send() set mctrl according to rts state. Date: Wed, 6 Jun 2018 11:49:38 +0200 Message-ID: <20180606094942.71190-2-giulio.benetti@micronovasrl.com> References: <20180606094942.71190-1-giulio.benetti@micronovasrl.com> Return-path: In-Reply-To: <20180606094942.71190-1-giulio.benetti@micronovasrl.com> Sender: linux-kernel-owner@vger.kernel.org Cc: matwey.kornilov@gmail.com, Giulio Benetti , Greg Kroah-Hartman , Jiri Slaby , Andy Shevchenko , Matthias Brugger , Kees Cook , Sean Young , Aaron Sierra , Tomas Melin , Sean Wang , Rafael Gago , Joel Stanley , "open list:SERIAL DRIVERS" , open list List-Id: linux-serial@vger.kernel.org When rs485 enabled and RTS_AFTER_SEND set on startup, need to preserve mctrl status, because later functions will call set_mctrl passing port->mctrl=0 overriding rts status, resulting in rts pin in transmission when idle. Make mctrl reflect rts pin state. Signed-off-by: Giulio Benetti --- drivers/tty/serial/8250/8250_port.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 95833cbc4338..c8c10b5ec6d6 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -562,10 +562,13 @@ static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p) { unsigned char mcr = serial8250_in_MCR(p); - if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND) + if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND) { mcr |= UART_MCR_RTS; - else + p->port.mctrl |= TIOCM_RTS; + } else { mcr &= ~UART_MCR_RTS; + p->port.mctrl &= ~TIOCM_RTS; + } serial8250_out_MCR(p, mcr); } -- 2.17.1