[PATCH 1/8] serial: core: only get RS485 termination gpio if supported
From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Date: 2022-06-22 15:48:07
Also in:
linux-arm-kernel, linux-serial, lkml
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
From: Lino Sanfilippo <redacted> In uart_get_rs485_mode() only try to get a termination GPIO if RS485 bus termination is supported by the driver. Signed-off-by: Lino Sanfilippo <redacted> --- drivers/tty/serial/serial_core.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 1368b0ef7d7f..015f4e1da647 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c@@ -3384,17 +3384,20 @@ int uart_get_rs485_mode(struct uart_port *port) rs485conf->flags |= SER_RS485_RTS_AFTER_SEND; } - /* - * Disabling termination by default is the safe choice: Else if many - * bus participants enable it, no communication is possible at all. - * Works fine for short cables and users may enable for longer cables. - */ - port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term", - GPIOD_OUT_LOW); - if (IS_ERR(port->rs485_term_gpio)) { - ret = PTR_ERR(port->rs485_term_gpio); - port->rs485_term_gpio = NULL; - return dev_err_probe(dev, ret, "Cannot get rs485-term-gpios\n"); + if (port->rs485_supported->flags & SER_RS485_TERMINATE_BUS) { + /* + * Disabling termination by default is the safe choice: Else if + * many bus participants enable it, no communication is possible + * at all. Works fine for short cables and users may enable for + * longer cables. + */ + port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term", + GPIOD_OUT_LOW); + if (IS_ERR(port->rs485_term_gpio)) { + ret = PTR_ERR(port->rs485_term_gpio); + port->rs485_term_gpio = NULL; + return dev_err_probe(dev, ret, "Cannot get rs485-term-gpios\n"); + } } return 0;
--
2.36.1