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Subject[PATCH 3/4] serial: 8250: Make em485_rts_after_send() set mctrl according to rts state.
Date
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 <giulio.benetti@micronovasrl.com>
---
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
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