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serial: core, imx: do not set RS485 enabled if it is not supported

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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: 00d7a00e2a ("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>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20240103061818.564-6-l.sanfilippo@kunbus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lino Sanfilippo 2024-01-03 07:18:16 +01:00 committed by Greg Kroah-Hartman
parent c73986913f
commit 74eab89b26
2 changed files with 3 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
drivers/tty/serial/imx.c
View file

@ -2211,7 +2211,6 @@ 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,
@ -2295,8 +2294,6 @@ 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);
@ -2331,10 +2328,6 @@ static int imx_uart_probe(struct platform_device *pdev)
if (ret)
goto err_clk;
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

3
drivers/tty/serial/serial_core.c
View file

@ -3607,6 +3607,9 @@ 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) {