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Subject[PATCH 4/4] serial: core: Mask mctrl with TIOCM_RTS too if rs485 on and RTS_AFTER_SEND set.
Date
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);

/*
--
2.17.1
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