If the imx driver cannot support RS485 it nullifies the ports rs485_supported structure. But it still calls uart_get_rs485_mode() which may set the RS485_ENABLED flag nevertheless.

This may lead to an attempt to configure RS485 even if it is not supported when the flag is evaluated in uart_configure_port() at port startup.

Avoid this by bailing out of uart_get_rs485_mode() if the RS485_ENABLED flag is not supported by the caller.

With this fix a check for RTS availability is now obsolete in the imx driver, since it can not evaluate to true any more. So remove this check.

Furthermore the explicit nullifcation of rs485_supported is not needed, since the memory has already been set to zeros at allocation. So remove this, too.

Fixes: 00d7a00e2a6f ("serial: imx: Fill in rs485_supported") Cc: Shawn Guo shawnguo@kernel.org Cc: Sascha Hauer s.hauer@pengutronix.de Cc: stable@vger.kernel.org Suggested-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Signed-off-by: Lino Sanfilippo l.sanfilippo@kunbus.com --- drivers/tty/serial/imx.c | 7 ------- drivers/tty/serial/serial_core.c | 3 +++ 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 9cffeb23112b..198ce7e7bc8b 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -2206,7 +2206,6 @@ static enum hrtimer_restart imx_trigger_stop_tx(struct hrtimer *t) return HRTIMER_NORESTART; }

-static const struct serial_rs485 imx_no_rs485 = {}; /* No RS485 if no RTS */ static const struct serial_rs485 imx_rs485_supported = { .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX, @@ -2290,8 +2289,6 @@ static int imx_uart_probe(struct platform_device *pdev) /* RTS is required to control the RS485 transmitter */ if (sport->have_rtscts || sport->have_rtsgpio) sport->port.rs485_supported = imx_rs485_supported; - else - sport->port.rs485_supported = imx_no_rs485; sport->port.flags = UPF_BOOT_AUTOCONF; timer_setup(&sport->timer, imx_uart_timeout, 0);

@@ -2328,10 +2325,6 @@ static int imx_uart_probe(struct platform_device *pdev) return ret; }

- if (sport->port.rs485.flags & SER_RS485_ENABLED && - (!sport->have_rtscts && !sport->have_rtsgpio)) - dev_err(&pdev->dev, "no RTS control, disabling rs485\n"); - /* * If using the i.MX UART RTS/CTS control then the RTS (CTS_B) * signal cannot be set low during transmission in case the diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 28bcbc686c67..93e4e1693601 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -3600,6 +3600,9 @@ int uart_get_rs485_mode(struct uart_port *port) u32 rs485_delay[2]; int ret;

+ if (!(port->rs485_supported.flags & SER_RS485_ENABLED)) + return 0; + ret = device_property_read_u32_array(dev, "rs485-rts-delay", rs485_delay, 2); if (!ret) {