[PATCH 0/6] Fixes and improvements for RS485

[PATCH 0/6] Fixes and improvements for RS485

[Lino Sanfilippo]

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Patch 1: Do not hold the port lock when setting rx-during-tx GPIO
Patch 2: Get rid of useless wrapper pl011_get_rs485_mode()
Patch 3: set missing supported flag for RX during TX GPIO
Patch 4: fix sanitizing check for RTS settings
Patch 5: make sure RS485 is cannot be enabled when it is not supported
Patch 6: IMX: do not set RS485 enabled if it is not supported


Lino Sanfilippo (6):
  serial: Do not hold the port lock when setting rx-during-tx GPIO
  serial: amba-pl011: get rid of useless wrapper pl011_get_rs485_mode()
  serial: core: set missing supported flag for RX during TX GPIO
  serial: core: fix sanitizing check for RTS settings
  serial: core: make sure RS485 is cannot be enabled when it is not
    supported
  serial: imx: do not set RS485 enabled if it is not supported

 drivers/tty/serial/amba-pl011.c  | 14 +---------
 drivers/tty/serial/imx.c         | 18 +++++--------
 drivers/tty/serial/serial_core.c | 45 +++++++++++++++++++++-----------
 drivers/tty/serial/stm32-usart.c |  5 +---
 4 files changed, 38 insertions(+), 44 deletions(-)


base-commit: 9ed22ae6be817d7a3f5c15ca22cbc9d3963b481d
-- 
2.40.1

[PATCH 1/6] serial: Do not hold the port lock when setting rx-during-tx GPIO

[Lino Sanfilippo]

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Both the imx and stm32 driver set the rx-during-tx GPIO in the
rs485_config() function by means of gpiod_set_value(). Since rs485_config()
is called with the port lock held, this can be an problem in case that
setting the GPIO line can sleep (e.g. if a GPIO expander is used which is
connected via SPI or I2C).

Avoid this issue by setting the GPIO outside of the port lock in the serial
core and by using gpiod_set_value_cansleep() instead of gpiod_set_value().

Since now both the term and the rx-during-tx GPIO are set within the serial
core use a common function uart_set_rs485_gpios() to set both.

With moving it into the serial core setting the rx-during-tx GPIO is now
automatically done for all drivers that support such a GPIO.

Cc: stable@vger.kernel.org
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
---
 drivers/tty/serial/imx.c         |  4 ----
 drivers/tty/serial/serial_core.c | 10 ++++++----
 drivers/tty/serial/stm32-usart.c |  5 +----
 3 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 13cb78340709..edb2ec6a5567 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1947,10 +1947,6 @@ static int imx_uart_rs485_config(struct uart_port *port, struct ktermios *termio
 	    rs485conf->flags & SER_RS485_RX_DURING_TX)
 		imx_uart_start_rx(port);
 
-	if (port->rs485_rx_during_tx_gpio)
-		gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio,
-					 !!(rs485conf->flags & SER_RS485_RX_DURING_TX));
-
 	return 0;
 }
 
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 7bdc21d5e13b..ef0500be3553 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1391,14 +1391,16 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
 	memset(rs485->padding1, 0, sizeof(rs485->padding1));
 }
 
-static void uart_set_rs485_termination(struct uart_port *port,
-				       const struct serial_rs485 *rs485)
+static void uart_set_rs485_gpios(struct uart_port *port,
+				 const struct serial_rs485 *rs485)
 {
 	if (!(rs485->flags & SER_RS485_ENABLED))
 		return;
 
 	gpiod_set_value_cansleep(port->rs485_term_gpio,
 				 !!(rs485->flags & SER_RS485_TERMINATE_BUS));
+	gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio,
+				 !!(rs485->flags & SER_RS485_RX_DURING_TX));
 }
 
 static int uart_rs485_config(struct uart_port *port)
@@ -1407,7 +1409,7 @@ static int uart_rs485_config(struct uart_port *port)
 	int ret;
 
 	uart_sanitize_serial_rs485(port, rs485);
-	uart_set_rs485_termination(port, rs485);
+	uart_set_rs485_gpios(port, rs485);
 
 	ret = port->rs485_config(port, NULL, rs485);
 	if (ret)
@@ -1449,7 +1451,7 @@ static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
 	if (ret)
 		return ret;
 	uart_sanitize_serial_rs485(port, &rs485);
-	uart_set_rs485_termination(port, &rs485);
+	uart_set_rs485_gpios(port, &rs485);
 
 	spin_lock_irqsave(&port->lock, flags);
 	ret = port->rs485_config(port, &tty->termios, &rs485);
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 5e9cf0c48813..8eb13bf055f2 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -226,10 +226,7 @@ static int stm32_usart_config_rs485(struct uart_port *port, struct ktermios *ter
 
 	stm32_usart_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
 
-	if (port->rs485_rx_during_tx_gpio)
-		gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio,
-					 !!(rs485conf->flags & SER_RS485_RX_DURING_TX));
-	else
+	if (!port->rs485_rx_during_tx_gpio)
 		rs485conf->flags |= SER_RS485_RX_DURING_TX;
 
 	if (rs485conf->flags & SER_RS485_ENABLED) {
-- 
2.40.1

Re: [PATCH 1/6] serial: Do not hold the port lock when setting rx-during-tx GPIO

[Greg KH]

On Fri, Sep 29, 2023 at 12:12:41AM +0200, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> 
> Both the imx and stm32 driver set the rx-during-tx GPIO in the
> rs485_config() function by means of gpiod_set_value(). Since rs485_config()
> is called with the port lock held, this can be an problem in case that
> setting the GPIO line can sleep (e.g. if a GPIO expander is used which is
> connected via SPI or I2C).
> 
> Avoid this issue by setting the GPIO outside of the port lock in the serial
> core and by using gpiod_set_value_cansleep() instead of gpiod_set_value().
> 
> Since now both the term and the rx-during-tx GPIO are set within the serial
> core use a common function uart_set_rs485_gpios() to set both.
> 
> With moving it into the serial core setting the rx-during-tx GPIO is now
> automatically done for all drivers that support such a GPIO.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>

You cc: stable on many of these, but do not provide a "Fixes:" tag
showing just how far back they should go.  Can you do that so that we
have a hint as to what to do here?

thanks,

greg k-h

Re: [PATCH 1/6] serial: Do not hold the port lock when setting rx-during-tx GPIO

[Lino Sanfilippo]

Hi,

On 29.09.23 07:50, Greg KH wrote:
> On Fri, Sep 29, 2023 at 12:12:41AM +0200, Lino Sanfilippo wrote:
>> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>>
>> Both the imx and stm32 driver set the rx-during-tx GPIO in the
>> rs485_config() function by means of gpiod_set_value(). Since rs485_config()
>> is called with the port lock held, this can be an problem in case that
>> setting the GPIO line can sleep (e.g. if a GPIO expander is used which is
>> connected via SPI or I2C).
>>
>> Avoid this issue by setting the GPIO outside of the port lock in the serial
>> core and by using gpiod_set_value_cansleep() instead of gpiod_set_value().
>>
>> Since now both the term and the rx-during-tx GPIO are set within the serial
>> core use a common function uart_set_rs485_gpios() to set both.
>>
>> With moving it into the serial core setting the rx-during-tx GPIO is now
>> automatically done for all drivers that support such a GPIO.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>
> You cc: stable on many of these, but do not provide a "Fixes:" tag
> showing just how far back they should go.  Can you do that so that we
> have a hint as to what to do here?
>

Yes, will do so in the next version.

BR,
Lino

> thanks,
>
> greg k-h

[PATCH 2/6] serial: amba-pl011: get rid of useless wrapper pl011_get_rs485_mode()

[Lino Sanfilippo]

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Due to earlier code changes function pl011_get_rs485_mode() is now merely
a wrapper for uart_get_rs485_mode() which does not add any further
functionality. So remove it and instead call uart_get_rs485_mode()
directly.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
---
 drivers/tty/serial/amba-pl011.c | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 3dc9b0fcab1c..70b44f3e9eb7 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2716,18 +2716,6 @@ static int pl011_find_free_port(void)
 	return -EBUSY;
 }
 
-static int pl011_get_rs485_mode(struct uart_amba_port *uap)
-{
-	struct uart_port *port = &uap->port;
-	int ret;
-
-	ret = uart_get_rs485_mode(port);
-	if (ret)
-		return ret;
-
-	return 0;
-}
-
 static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
 			    struct resource *mmiobase, int index)
 {
@@ -2748,7 +2736,7 @@ static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
 	uap->port.flags = UPF_BOOT_AUTOCONF;
 	uap->port.line = index;
 
-	ret = pl011_get_rs485_mode(uap);
+	ret = uart_get_rs485_mode(&uap->port);
 	if (ret)
 		return ret;
 
-- 
2.40.1

Re: [PATCH 2/6] serial: amba-pl011: get rid of useless wrapper pl011_get_rs485_mode()

[Lukas Wunner]

On Fri, Sep 29, 2023 at 12:12:42AM +0200, Lino Sanfilippo wrote:
> Due to earlier code changes function pl011_get_rs485_mode() is now merely
> a wrapper for uart_get_rs485_mode() which does not add any further
> functionality. So remove it and instead call uart_get_rs485_mode()
> directly.
> 
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Reviewed-by: Lukas Wunner <lukas@wunner.de>

[PATCH 3/6] serial: core: set missing supported flag for RX during TX GPIO

[Lino Sanfilippo]

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

If the RS485 feature RX-during-TX is supported by means of a GPIO set the
according supported flag. Otherwise setting this feature from userspace may
not be possible, since in uart_sanitize_serial_rs485() the passed RS485
configuration is matched against the supported features and unsupported
settings are thereby removed and thus take no effect.

Cc: stable@vger.kernel.org
Fixes: 163f080eb717 ("serial: core: Add option to output RS485 RX_DURING_TX state via GPIO")
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
---
 drivers/tty/serial/serial_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index ef0500be3553..697c36dc7ec8 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3622,6 +3622,8 @@ int uart_get_rs485_mode(struct uart_port *port)
 		port->rs485_rx_during_tx_gpio = NULL;
 		return dev_err_probe(dev, ret, "Cannot get rs485-rx-during-tx-gpios\n");
 	}
+	if (port->rs485_rx_during_tx_gpio)
+		port->rs485_supported.flags |= SER_RS485_RX_DURING_TX;
 
 	return 0;
 }
-- 
2.40.1

[PATCH 4/6] serial: core: fix sanitizing check for RTS settings

[Lino Sanfilippo]

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Among other things uart_sanitize_serial_rs485() tests the sanity of the RTS
settings in a RS485 configuration that has been passed by userspace.
If RTS-on-send and RTS-after-send are both set or unset the configuration
is adjusted and RTS-after-send is disabled and RTS-on-send enabled.

This however makes only sense if both RTS modes are actually supported by
the driver.

With commit be2e2cb1d281 ("serial: Sanitize rs485_struct") the code does
take the driver support into account but only checks if one of both RTS
modes are supported. This may lead to the errorneous result of RTS-on-send
being set even if only RTS-after-send is supported.

Fix this by changing the implemented logic: First clear all unsupported
flags in the RS485 configuration, then adjust an invalid RTS setting by
taking into account which RTS mode is supported.

Cc: stable@vger.kernel.org
Fixes: be2e2cb1d281 ("serial: Sanitize rs485_struct")
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
---
 drivers/tty/serial/serial_core.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 697c36dc7ec8..f4feebf8200f 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1370,19 +1370,27 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4
 		return;
 	}
 
+	rs485->flags &= supported_flags;
+
 	/* Pick sane settings if the user hasn't */
-	if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
-	    !(rs485->flags & SER_RS485_RTS_ON_SEND) ==
+	if (!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
 	    !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
-		dev_warn_ratelimited(port->dev,
-			"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
-			port->name, port->line);
-		rs485->flags |= SER_RS485_RTS_ON_SEND;
-		rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
-		supported_flags |= SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND;
-	}
+		if (supported_flags & SER_RS485_RTS_ON_SEND) {
+			rs485->flags |= SER_RS485_RTS_ON_SEND;
+			rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
 
-	rs485->flags &= supported_flags;
+			dev_warn_ratelimited(port->dev,
+				"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
+				port->name, port->line);
+		} else {
+			rs485->flags |= SER_RS485_RTS_AFTER_SEND;
+			rs485->flags &= ~SER_RS485_RTS_ON_SEND;
+
+			dev_warn_ratelimited(port->dev,
+				"%s (%d): invalid RTS setting, using RTS_AFTER_SEND instead\n",
+				port->name, port->line);
+		}
+	}
 
 	uart_sanitize_serial_rs485_delays(port, rs485);
 
-- 
2.40.1

[PATCH 5/6] serial: core: make sure RS485 is cannot be enabled when it is not supported

[Lino Sanfilippo]

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Some uart drivers specify a rs485_config() function and then decide later
to disable RS485 support for some reason (e.g. imx and ar933).

In these cases userspace may be able to activate RS485 via TIOCSRS485
nevertheless, since in uart_set_rs485_config() an existing rs485_config()
function indicates that RS485 is supported.

Make sure that this is not longer possible by checking the uarts
rs485_supported.flags instead and bailing out if SER_RS485_ENABLED is not
set.

Furthermore instead of returning an empty structure return -ENOTTY if the
RS485 configuration is requested via TIOCGRS485 but RS485 is not supported.

Cc: stable@vger.kernel.org
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
---
 drivers/tty/serial/serial_core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index f4feebf8200f..dca09877fabc 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1432,6 +1432,9 @@ static int uart_get_rs485_config(struct uart_port *port,
 	unsigned long flags;
 	struct serial_rs485 aux;
 
+	if (!(port->rs485_supported.flags & SER_RS485_ENABLED))
+		return -ENOTTY;
+
 	spin_lock_irqsave(&port->lock, flags);
 	aux = port->rs485;
 	spin_unlock_irqrestore(&port->lock, flags);
@@ -1449,7 +1452,7 @@ static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
 	int ret;
 	unsigned long flags;
 
-	if (!port->rs485_config)
+	if (!(port->rs485_supported.flags & SER_RS485_ENABLED))
 		return -ENOTTY;
 
 	if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
-- 
2.40.1

Re: [PATCH 5/6] serial: core: make sure RS485 is cannot be enabled when it is not supported

[Hugo Villeneuve]

Hi,
remove superfluous "is" after RS485 in patch title.

Hugo.



On Fri, 29 Sep 2023 00:12:45 +0200
Lino Sanfilippo <LinoSanfilippo@gmx.de> wrote:

> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> 
> Some uart drivers specify a rs485_config() function and then decide later
> to disable RS485 support for some reason (e.g. imx and ar933).
> 
> In these cases userspace may be able to activate RS485 via TIOCSRS485
> nevertheless, since in uart_set_rs485_config() an existing rs485_config()
> function indicates that RS485 is supported.
> 
> Make sure that this is not longer possible by checking the uarts
> rs485_supported.flags instead and bailing out if SER_RS485_ENABLED is not
> set.
> 
> Furthermore instead of returning an empty structure return -ENOTTY if the
> RS485 configuration is requested via TIOCGRS485 but RS485 is not supported.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> ---
>  drivers/tty/serial/serial_core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index f4feebf8200f..dca09877fabc 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -1432,6 +1432,9 @@ static int uart_get_rs485_config(struct uart_port *port,
>  	unsigned long flags;
>  	struct serial_rs485 aux;
>  
> +	if (!(port->rs485_supported.flags & SER_RS485_ENABLED))
> +		return -ENOTTY;
> +
>  	spin_lock_irqsave(&port->lock, flags);
>  	aux = port->rs485;
>  	spin_unlock_irqrestore(&port->lock, flags);
> @@ -1449,7 +1452,7 @@ static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
>  	int ret;
>  	unsigned long flags;
>  
> -	if (!port->rs485_config)
> +	if (!(port->rs485_supported.flags & SER_RS485_ENABLED))
>  		return -ENOTTY;
>  
>  	if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
> -- 
> 2.40.1
> 

Re: [PATCH 5/6] serial: core: make sure RS485 is cannot be enabled when it is not supported

[Lino Sanfilippo]

Hi,

On 29.09.23 14:17, Hugo Villeneuve wrote:
> Hi,
> remove superfluous "is" after RS485 in patch title.
>
> Hugo.
>

Indeed, I will fix this, thanks!

BR,
Lino

[PATCH 6/6] serial: imx: do not set RS485 enabled if it is not supported

[Lino Sanfilippo]

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

If the imx driver cannot support RS485 it sets the UARTS rs485_supported
structure to NULL. But it still calls uart_get_rs485_mode() which may set
the RS485_ENABLED flag.
The flag however is evaluated by the serial core in uart_configure_port()
at port startup and thus may lead to an attempt to configure RS485 even if
it is not supported.

Avoid this by calling uart_get_rs485_mode() only if RS485 is actually
supported by the driver. Remove also a check for an error condition
that is not possible any more now.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
---
 drivers/tty/serial/imx.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index edb2ec6a5567..87689abc21bd 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2326,16 +2326,14 @@ static int imx_uart_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = uart_get_rs485_mode(&sport->port);
-	if (ret) {
-		clk_disable_unprepare(sport->clk_ipg);
-		return ret;
+	if (sport->port.rs485_supported.flags & SER_RS485_ENABLED) {
+		ret = uart_get_rs485_mode(&sport->port);
+		if (ret) {
+			clk_disable_unprepare(sport->clk_ipg);
+			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
-- 
2.40.1

Re: [PATCH 6/6] serial: imx: do not set RS485 enabled if it is not supported

[Greg KH]

On Fri, Sep 29, 2023 at 12:12:46AM +0200, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> 
> If the imx driver cannot support RS485 it sets the UARTS rs485_supported
> structure to NULL. But it still calls uart_get_rs485_mode() which may set
> the RS485_ENABLED flag.
> The flag however is evaluated by the serial core in uart_configure_port()
> at port startup and thus may lead to an attempt to configure RS485 even if
> it is not supported.
> 
> Avoid this by calling uart_get_rs485_mode() only if RS485 is actually
> supported by the driver. Remove also a check for an error condition
> that is not possible any more now.
> 
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> ---
>  drivers/tty/serial/imx.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)

Why is this patch not marked for stable?

thanks,

greg k-h

Re: [PATCH 6/6] serial: imx: do not set RS485 enabled if it is not supported

[Lino Sanfilippo]

On 29.09.23 07:51, Greg KH wrote:
> On Fri, Sep 29, 2023 at 12:12:46AM +0200, Lino Sanfilippo wrote:
>> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>>
>> If the imx driver cannot support RS485 it sets the UARTS rs485_supported
>> structure to NULL. But it still calls uart_get_rs485_mode() which may set
>> the RS485_ENABLED flag.
>> The flag however is evaluated by the serial core in uart_configure_port()
>> at port startup and thus may lead to an attempt to configure RS485 even if
>> it is not supported.
>>
>> Avoid this by calling uart_get_rs485_mode() only if RS485 is actually
>> supported by the driver. Remove also a check for an error condition
>> that is not possible any more now.
>>
>> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>> ---
>>  drivers/tty/serial/imx.c | 14 ++++++--------
>>  1 file changed, 6 insertions(+), 8 deletions(-)
>
> Why is this patch not marked for stable?
>

Right, it should be, I will correct this, thanks!

Re: [PATCH 6/6] serial: imx: do not set RS485 enabled if it is not supported

[Uwe Kleine-König]

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On Fri, Sep 29, 2023 at 12:12:46AM +0200, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> 
> If the imx driver cannot support RS485 it sets the UARTS rs485_supported
> structure to NULL. But it still calls uart_get_rs485_mode() which may set
> the RS485_ENABLED flag.
> The flag however is evaluated by the serial core in uart_configure_port()

I wonder if this is the code location where this problem should be
addressed. Or alternatively don't let uart_get_rs485_mode() set
RS485_ENABLED (and other flags) if rs485_supported doesn't suggest that
this works?

> [...]
> 
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>

I don't know how picky Greg is here, but formally you missed to add an
S-o-b line for the sender of this patch (i.e. you with your gmx
address).

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH 6/6] serial: imx: do not set RS485 enabled if it is not supported

[Lino Sanfilippo]

Hi,

On 29.09.23 08:39, Uwe Kleine-König wrote:
> On Fri, Sep 29, 2023 at 12:12:46AM +0200, Lino Sanfilippo wrote:
>> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>>
>> If the imx driver cannot support RS485 it sets the UARTS rs485_supported
>> structure to NULL. But it still calls uart_get_rs485_mode() which may set
>> the RS485_ENABLED flag.
>> The flag however is evaluated by the serial core in uart_configure_port()
>
> I wonder if this is the code location where this problem should be
> addressed. Or alternatively don't let uart_get_rs485_mode() set
> RS485_ENABLED (and other flags) if rs485_supported doesn't suggest that
> this works?
>

This is indeed the better solution. Especially since the check is then in the serial
core and all RS485 supporting drivers benefit from it. I will change this for v2, thanks!


>> [...]
>>
>> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>
> I don't know how picky Greg is here, but formally you missed to add an
> S-o-b line for the sender of this patch (i.e. you with your gmx
> address).
>

Hm, until now there have never been complaints about this. Is this really an issue? Of
course I can also S-o-b with my gmx address but adding two S-o-b's for the same person seems
a bit odd to me...

BR,
Lino

> Best regards
> Uwe
>

Re: [PATCH 6/6] serial: imx: do not set RS485 enabled if it is not supported

[Uwe Kleine-König]

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Hello Lino,

On Fri, Sep 29, 2023 at 03:46:52PM +0200, Lino Sanfilippo wrote:
> On 29.09.23 08:39, Uwe Kleine-König wrote:
> > On Fri, Sep 29, 2023 at 12:12:46AM +0200, Lino Sanfilippo wrote:
> >> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> >
> > I don't know how picky Greg is here, but formally you missed to add an
> > S-o-b line for the sender of this patch (i.e. you with your gmx
> > address).
> >
> 
> Hm, until now there have never been complaints about this. Is this really an issue? Of
> course I can also S-o-b with my gmx address but adding two S-o-b's for the same person seems
> a bit odd to me...

The obvious and easy fix is of course to use the author address to send
the patches. :-)

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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