linux-kernel - [PATCH 1/2] serial: stm32: do not always set SER_RS485_RX_DURING

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Date: Fri, 16 Feb 2024 23:47:07 +0100
From: Lino Sanfilippo <l.sanfilippo@...bus.com>
To: gregkh@...uxfoundation.org,
	jirislaby@...nel.org
Cc: LinoSanfilippo@....de,
	lukas@...ner.de,
	p.rosenberger@...bus.com,
	ilpo.jarvinen@...ux.intel.com,
	mcoquelin.stm32@...il.com,
	alexandre.torgue@...s.st.com,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	Lino Sanfilippo <l.sanfilippo@...bus.com>,
	stable@...r.kernel.org
Subject: [PATCH 1/2] serial: stm32: do not always set SER_RS485_RX_DURING_TX if RS485 is enabled

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@...r.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@...bus.com>
---
 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);

base-commit: 841c35169323cd833294798e58b9bf63fa4fa1de
-- 
2.43.0