Re: [PATCH v2 3/3] serial: core: Drive the transceiver interface select GPIO

[sashiko-bot@kernel.org]

> Multiprotocol transceivers such as the LTC2873 provide both an RS232
> and an RS485 interface on the same bus pins and choose between them
> with an interface select input. There is no generic way to drive that
> input today, so a port wired to such a transceiver is stuck in
> whichever interface the pin is strapped to.
> 
> Add the optional rs485-select-gpios property to the GPIOs acquired by
> uart_get_rs485_mode() and drive it from the RS485 configuration state:
> the GPIO is active while RS485 is enabled, which selects the RS485
> interface, and inactive otherwise, which selects the alternative
> interface, typically RS232. RS422 is a mode of SER_RS485_ENABLED and
> therefore selects the RS485 interface as well.
> 
> The state is applied in uart_rs485_config() for the boot-time and
> resume paths and in uart_set_rs485_config() for the ioctl path. Unlike
> [ ... ]
> 
> Drivers calling uart_get_rs485_mode() need no change to support such
> transceivers.
> 
> Signed-off-by: Tapio Reijonen <tapio.reijonen@vaisala.com>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261105-serial-rs485-mode-gpio-v2-0-027e5348892f@vaisala.com?part=3