Re: [PATCH 2/2] serial: amba-pl011: keep RS485 transmission running on reconfiguration

[sashiko-bot@kernel.org]

> Changing the RS485 settings while RS485 stays enabled calls
> pl011_rs485_tx_stop(), also while a transmission is in progress. Unlike
> pl011_stop_tx() it leaves the TX interrupt enabled, so the remaining
> data is still pushed into the FIFO after the drain turned off the
> transmitter. The FIFO never empties, the port stalls, and closing it
> hangs in pl011_dma_shutdown() waiting for the transmitter to go idle.
> A start still waiting for delay_rts_before_send is dropped as well.
> 
> Only stop the transmitter when no transmission is in progress. The
> call is still needed there, it sets the idle RTS level when the port
> is configured or resumed. A transmission in progress sets that level
> when it ends.
> 
> An active break counts as a transmission too. Forget it only when
> leaving RS485 mode, so that pl011_break_ctl() still ends the
> transmission when the break ends.
> 
> Fixes: 8d479237727c ("serial: amba-pl011: add RS485 support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20261016-devel-nbuchwitz-pl011-rs485-reconfig-stall-v1-0-f07d4da714be@tipi-net.de?part=2