[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <2023100450-charger-disregard-9683@gregkh>
Date: Wed, 4 Oct 2023 14:13:01 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Paul Geurts <paul_geurts@...e.nl>
Cc: jirislaby@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] serial: imx: fix tx statemachine deadlock
On Wed, Oct 04, 2023 at 11:57:22AM +0200, 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.
>
> Signed-off-by: Paul Geurts <paul_geurts@...e.nl>
> ---
> drivers/tty/serial/imx.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
What commit id does this fix?
thanks,
greg k-h
Powered by blists - more mailing lists