diff mbox series

[4/8] serial: core: sanitize RS485 delays read from device tree

Message ID 20220622154659.8710-5-LinoSanfilippo@gmx.de (mailing list archive)
State New, archived
Headers show
Series Fixes and cleanup for RS485 | expand

Commit Message

Lino Sanfilippo June 22, 2022, 3:46 p.m. UTC
From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

When setting the RS485 configuration from userspace via TIOCSRS485 the
delays are clamped to 100ms. Make this consistent with the values passed
in by means of device tree parameters.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
---
 drivers/tty/serial/serial_core.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Ilpo Järvinen June 25, 2022, 10:05 a.m. UTC | #1
On Wed, 22 Jun 2022, Lino Sanfilippo wrote:

> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> 
> When setting the RS485 configuration from userspace via TIOCSRS485 the
> delays are clamped to 100ms. Make this consistent with the values passed
> in by means of device tree parameters.
> 
> 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 fa6acadd7d0c..2e9f90e73e62 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -3382,6 +3382,8 @@ int uart_get_rs485_mode(struct uart_port *port)
>  		rs485conf->delay_rts_after_send = 0;
>  	}
>  
> +	uart_sanitize_serial_rs485_delays(port, rs485conf);
> +
>  	/*
>  	 * Clear full-duplex and enabled flags, set RTS polarity to active high
>  	 * to get to a defined state with the following properties:
> -- 
> 2.36.1

While above works, if we go to this change user-visible behavior route, 
uart_get_rs485_mode() could just call full uart_sanitize_serial_rs485()?

The sanitization is currently being done during probe in 
uart_rs485_config() which has another challenge to tackle. The RS485 
supporting UART drivers are not consistently calling it during their 
probe(), only a few of them do but it would make more sense if all of them 
would enter into RS485 mode w/  linux,rs485-enabled-at-boot-time being 
set. However, making such change might run afoul with the expectations of 
users.
Lino Sanfilippo June 26, 2022, 2:25 p.m. UTC | #2
On 25.06.22 at 12:05, Ilpo Järvinen wrote:
> On Wed, 22 Jun 2022, Lino Sanfilippo wrote:
>
>> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>>
>> When setting the RS485 configuration from userspace via TIOCSRS485 the
>> delays are clamped to 100ms. Make this consistent with the values passed
>> in by means of device tree parameters.
>>
>> 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 fa6acadd7d0c..2e9f90e73e62 100644
>> --- a/drivers/tty/serial/serial_core.c
>> +++ b/drivers/tty/serial/serial_core.c
>> @@ -3382,6 +3382,8 @@ int uart_get_rs485_mode(struct uart_port *port)
>>  		rs485conf->delay_rts_after_send = 0;
>>  	}
>>
>> +	uart_sanitize_serial_rs485_delays(port, rs485conf);
>> +
>>  	/*
>>  	 * Clear full-duplex and enabled flags, set RTS polarity to active high
>>  	 * to get to a defined state with the following properties:
>> --
>> 2.36.1
>
> While above works, if we go to this change user-visible behavior route,
> uart_get_rs485_mode() could just call full uart_sanitize_serial_rs485()?

As it is now uart_sanitize_serial_rs485() will clear the entire serial_rs485 struct and
return immediately if rs485-enabled-at-boot-time (and thus SER_RS485_ENABLED)
is not set. That was one of the reasons I moved the delay checks into an own fucntion. The other
reason is that the remaining sanity check for RTS on send/after send in uart_sanitize_serial_rs485() is not
required in uart_get_rs485_mode() since here we already ensure a sane setting.

Regards,
Lino
diff mbox series

Patch

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index fa6acadd7d0c..2e9f90e73e62 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3382,6 +3382,8 @@  int uart_get_rs485_mode(struct uart_port *port)
 		rs485conf->delay_rts_after_send = 0;
 	}
 
+	uart_sanitize_serial_rs485_delays(port, rs485conf);
+
 	/*
 	 * Clear full-duplex and enabled flags, set RTS polarity to active high
 	 * to get to a defined state with the following properties: