On Wed, 3 Jan 2024, Lino Sanfilippo wrote:
> 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@xxxxxxxxxx>
> Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Suggested-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
> ---
> 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;
> +
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
--
i.
