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Date:   Sat, 9 Dec 2023 12:47:47 +0100
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Subject: Re: [PATCH 1/2] dt-bindings: serial: rs485: add rs485-mux-gpios
 binding
Content-Language: en-US
From:   Lino Sanfilippo <LinoSanfilippo@gmx.de>
To:     Christoph Niedermaier <cniedermaier@dh-electronics.com>,
        Lukas Wunner <lukas@wunner.de>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
        =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
        "brenda.streiff@ni.com" <brenda.streiff@ni.com>,
        Crescent CY Hsieh <crescentcy.hsieh@moxa.com>,
        Tomas Paukrt <tomaspaukrt@email.cz>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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Precedence: bulk


On 06.12.23 16:42, Lino Sanfilippo wrote:
>

>>>>
>>>> Crescent CY Hsieh (+cc) is in parallel trying to add an RS-422 mode b=
it
>>>> to struct serial_rs485:
>>>>
>>>> https://lore.kernel.org/all/20231121095122.15948-1-crescentcy.hsieh@m=
oxa.com/
>>>>
>>>
>>> That new flag was suggested by me instead of using SER_RS422_ENABLED, =
which
>>> would mostly be redundant to SER_RS485_ENABLED.

A cleaner solution would probably be to not handle RS422 with the RS485 se=
ttings at
all, but to introduce another set of ioctls to set and read it.

An own RS422 structure like

struct serial_rs422 {
	__u32	flags;
#define SER_RS422_ENABLED		(1 << 0)
#define SER_RS422_TERMINATE_BUS		(1 << 1)
};


could be used as the parameter for these new ioctls.

Any comments on this?


Regards,
Lino