From: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
To: Paul Geurts <paul_geurts@live.nl>,
gregkh@linuxfoundation.org, jirislaby@kernel.org,
shawnguo@kernel.org, s.hauer@pengutronix.de,
kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com,
u.kleine-koenig@pengutronix.de, linux-kernel@vger.kernel.org,
linux-serial@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Cc: Eberhard Stoll <eberhard.stoll@gmx.de>
Subject: Re: [PATCH v3] serial: imx: fix tx statemachine deadlock
Date: Fri, 24 Nov 2023 14:37:11 +0100 [thread overview]
Message-ID: <a283cb15-d740-4f94-a81e-0147c2035cf7@prevas.dk> (raw)
In-Reply-To: <AM0PR09MB26758F651BC1B742EB45775995B8A@AM0PR09MB2675.eurprd09.prod.outlook.com>
On 24/11/2023 14.11, Paul Geurts wrote:
> When using the serial port as RS485 port, the tx statemachine is used to
> control the RTS pin to drive the RS485 transceiver TX_EN pin. When the
> TTY port is closed in the middle of a transmission (for instance during
> userland application crash), imx_uart_shutdown disables the interface
> and disables the Transmission Complete interrupt. afer that,
> imx_uart_stop_tx bails on an incomplete transmission, to be retriggered
> by the TC interrupt. This interrupt is disabled and therefore the tx
> statemachine never transitions out of SEND. The statemachine is in
> deadlock now, and the TX_EN remains low, making the interface useless.
>
> imx_uart_stop_tx now checks for incomplete transmission AND whether TC
> interrupts are enabled before bailing to be retriggered. This makes sure
> the state machine handling is reached, and is properly set to
> WAIT_AFTER_SEND.
>
> Fixes: cb1a60923609 ("serial: imx: implement rts delaying for rs485")
> Signed-off-by: Paul Geurts <paul_geurts@live.nl>
Hi Paul
Interestingly, both Eberhard (cc'ed) and I have hit similar problems in
this driver recently. See the thread
https://lore.kernel.org/lkml/20231120132256.136625-1-rasmus.villemoes@prevas.dk/
.
It is possible that this also fixes the problems I/we saw, but I can't
get around to testing until sometime next week.
Rasmus
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next prev parent reply other threads:[~2023-11-24 13:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-04 9:57 [PATCH] serial: imx: fix tx statemachine deadlock Paul Geurts
2023-10-04 10:20 ` Uwe Kleine-König
2023-10-05 8:51 ` Paul Geurts
2023-10-04 12:13 ` Greg KH
2023-11-24 12:38 ` [PATCH v2] " Paul Geurts
2023-11-24 12:45 ` Greg KH
2023-11-24 12:53 ` Paul Geurts
2023-11-24 12:58 ` Fabio Estevam
2023-11-24 13:03 ` Greg KH
2023-11-24 13:11 ` [PATCH v3] " Paul Geurts
2023-11-24 13:37 ` Rasmus Villemoes [this message]
2023-11-24 13:55 ` Paul Geurts
2023-11-30 9:09 ` Rasmus Villemoes
2023-12-01 16:55 ` Eberhard Stoll
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