[PATCH 6.6 181/299] serial: stm32: do not always set SER_RS485_RX_DURING_TX if RS485 is enabled

Greg Kroah-Hartman
2024-02-27T13:55:07Z

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

commit f418ae73311deb901c0110b08d1bbafc20c1820e upstream.

Before commit 07c30ea5861f ("serial: Do not hold the port lock when setting
rx-during-tx GPIO") the SER_RS485_RX_DURING_TX flag was only set if the
rx-during-tx mode was not controlled by a GPIO. Now the flag is set
unconditionally when RS485 is enabled. This results in an incorrect setting
if the rx-during-tx GPIO is not asserted.

Fix this by setting the flag only if the rx-during-tx mode is not
controlled by a GPIO and thus restore the correct behaviour.

Cc: stable@vger.kernel.org # 6.6+
Fixes: 07c30ea5861f ("serial: Do not hold the port lock when setting rx-during-tx GPIO")
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20240216224709.9928-1-l.sanfilippo@kunbus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/stm32-usart.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 794b77512740..693e932d6feb 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -251,7 +251,9 @@ static int stm32_usart_config_rs485(struct uart_port *port, struct ktermios *ter
writel_relaxed(cr3, port->membase + ofs->cr3);
writel_relaxed(cr1, port->membase + ofs->cr1);

- rs485conf->flags |= SER_RS485_RX_DURING_TX;
+ if (!port->rs485_rx_during_tx_gpio)
+ rs485conf->flags |= SER_RS485_RX_DURING_TX;
+
} else {
stm32_usart_clr_bits(port, ofs->cr3,
USART_CR3_DEM | USART_CR3_DEP);
--
2.44.0