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Date:   Wed, 13 Dec 2023 12:18:50 +0200 (EET)
From:   =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= <ilpo.jarvinen@linux.intel.com>
To:     Lino Sanfilippo <l.sanfilippo@kunbus.com>
cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        u.kleine-koenig@pengutronix.de, shawnguo@kernel.org,
        s.hauer@pengutronix.de, mcoquelin.stm32@gmail.com,
        alexandre.torgue@foss.st.com, cniedermaier@dh-electronics.com,
        hugo@hugovil.com, LKML <linux-kernel@vger.kernel.org>,
        linux-serial <linux-serial@vger.kernel.org>,
        LinoSanfilippo@gmx.de, Lukas Wunner <lukas@wunner.de>,
        p.rosenberger@kunbus.com, stable@vger.kernel.org
Subject: Re: [PATCH v5 7/7] serial: 8250_exar: Set missing rs485_supported
 flag
In-Reply-To: <20231209125836.16294-8-l.sanfilippo@kunbus.com>
Message-ID: <acca4f3e-2763-655-9968-bbaa9920d289@linux.intel.com>
References: <20231209125836.16294-1-l.sanfilippo@kunbus.com> <20231209125836.16294-8-l.sanfilippo@kunbus.com>
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On Sat, 9 Dec 2023, Lino Sanfilippo wrote:

> The UART supports an auto-RTS mode in which the RTS pin is automatically
> activated during transmission. So mark this mode as being supported even
> if RTS is not controlled by the driver but the UART.
> 
> Also the serial core expects now at least one of both modes rts-on-send or
> rts-after-send to be supported. This is since during sanitization
> unsupported flags are deleted from a RS485 configuration set by userspace.
> However if the configuration ends up with both flags unset, the core prints
> a warning since it considers such a configuration invalid (see
> uart_sanitize_serial_rs485()).
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> ---
>  drivers/tty/serial/8250/8250_exar.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
> index 6085d356ad86..23366f868ae3 100644
> --- a/drivers/tty/serial/8250/8250_exar.c
> +++ b/drivers/tty/serial/8250/8250_exar.c
> @@ -480,7 +480,7 @@ static int sealevel_rs485_config(struct uart_port *port, struct ktermios *termio
>  }
>  
>  static const struct serial_rs485 generic_rs485_supported = {
> -	.flags = SER_RS485_ENABLED,
> +	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND,
>  };
>  
>  static const struct exar8250_platform exar8250_default_platform = {
> @@ -524,7 +524,8 @@ static int iot2040_rs485_config(struct uart_port *port, struct ktermios *termios
>  }
>  
>  static const struct serial_rs485 iot2040_rs485_supported = {
> -	.flags = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX | SER_RS485_TERMINATE_BUS,
> +	.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND |
> +		 SER_RS485_RX_DURING_TX | SER_RS485_TERMINATE_BUS,
>  };
>  
>  static const struct property_entry iot2040_gpio_properties[] = {

Reviewed-by: Ilpo J?rvinen <ilpo.jarvinen@linux.intel.com>

(I assume you picked the correct flag among the two alternatives).

-- 
 i.

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