This is a note to let you know that I've just added the patch titled
serial: core, imx: do not set RS485 enabled if it is not supported
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the tty-next branch sometime soon,
after it passes testing, and the merge window is open.
If you have any questions about this process, please let me know.
>From 74eab89b26ac433ad857292f4707b43c1a8f0209 Mon Sep 17 00:00:00 2001
From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Date: Wed, 3 Jan 2024 07:18:16 +0100
Subject: serial: core, imx: do not set RS485 enabled if it is not supported
MIME-Version: 1.0
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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: 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>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240103061818.564-6-l.sanfilippo@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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 8b7d9c5a7455..4aa72d5aeafb 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -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
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index b9606db78c92..b56ed8c376b2 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -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) {
--
2.43.0
