Re: [PATCH v2] serial: 8250_bcm2835aux: Add support for RTS/CTS auto flow control

[sashiko-bot@kernel.org]

> The bcm2835aux mini UART can automatically de-assert RTS based on the RX
> FIFO fill level and gate the transmitter on CTS, but the driver never
> made use of it. Wire it up:
> 
> - Enable AUTORTS/AUTOCTS (with the RTS4 threshold and inverted, i.e.
>   conventional active-low, polarity) whenever CRTSCTS is set on ports
>   declaring the "uart-has-rtscts" property, advertised via
>   UPF_HARD_FLOW.
> 
> - Gate the AUTORTS function on TIOCM_RTS in set_mctrl() so that clearing
>   RTS (port close, TIOCMBIC, B0) actually de-asserts the pin while auto
>   flow control is active.
> 
> - Implement throttle()/unthrottle() by disabling the RX interrupts and
>   letting the FIFO fill up, making the hardware de-assert RTS - the same
> [ ... ]
>   without the rs485_stop_tx() callback ever being called, which would
>   leave the receiver disabled.
> 
> Assisted-by: Claude:claude-fable-5
> Signed-off-by: Jan Čermák <sairon@sairon.cz>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260930125620.221836-1-sairon@sairon.cz?part=1