Re: [PATCH RESEND v4 1/2] serial: amba-pl011: finish a transmission still running when RS485 is enabled

[sashiko-bot@kernel.org]

> Disabling RS485 during a transmission keeps it running. If RS485 is
> enabled again before it ends, the state is OFF while data is still going
> out. The TX path does not end a transmission in state OFF, so nothing
> sets the idle RTS level afterwards and the transceiver keeps driving the
> bus.
> 
> Hand such a transmission back to RS485 when it is enabled on an open
> port. While PIO or DMA still feeds the FIFO, assert RTS and mark it as
> sending, so that the TX path ends it like any other. With only the FIFO
> left, drain it from trigger_stop_tx instead. Data that is queued but not
> started yet, for example while output is stopped, is not part of the
> transmission.
> 
> Fixes: 97f85204275a ("serial: amba-pl011: keep transmitter enabled when disabling RS485")
> Cc: stable@vger.kernel.org # 6.18.x: 1b6d660e038b: serial: amba-pl011: drive the bus during break in RS485 mode
> Cc: stable@vger.kernel.org # 6.18.x
> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261112-devel-nbuchwitz-pl011-rs485-reconfig-stall-v4-0-b5c58ff3a376@tipi-net.de?part=1