From: sashiko-bot@kernel.org
To: "Nicolai Buchwitz" <nb@tipi-net.de>
Cc: linux-serial@vger.kernel.org
Subject: Re: [PATCH v2] serial: amba-pl011: keep transmitter enabled when disabling RS485
Date: Mon, 12 Oct 2026 14:34:14 +0000 [thread overview]
Message-ID: <sashiko-outbox-168270@kernel.org> (raw)
In-Reply-To: <20261012-fix-pl011-rs485-txe-v2-1-e9bf7d218389@tipi-net.de>
> Disabling RS485 on an open port calls pl011_rs485_tx_stop(), which
> turns off the transmitter. Only the RS485 TX path turns it back on, so
> any later output stays queued and tcdrain() hangs until the port is
> closed.
>
> pl011_rs485_tx_stop() also checks only the hardware FIFO. If a DMA
> transfer has started but has not filled the FIFO yet, the transmitter
> is turned off under the transfer and the DMA channel never recovers.
>
> When leaving RS485 mode, cancel pending deferred starts and stops, leave
> the transmitter enabled and start any TX that was still waiting for
> delay_rts_before_send.
>
> 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!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261012-fix-pl011-rs485-txe-v2-1-e9bf7d218389@tipi-net.de?part=1
prev parent reply other threads:[~2026-10-12 14:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-12 14:23 [PATCH v2] serial: amba-pl011: keep transmitter enabled when disabling RS485 Nicolai Buchwitz
2026-10-12 14:34 ` sashiko-bot [this message]
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