linux-kernel - Re: [PATCH v2 2/2] serial: mxs-auart: fix tx

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Message-ID: <3935b841-77b7-4265-a727-98a358cd56be@kernel.org>
Date: Thu, 1 Feb 2024 13:05:42 +0100
From: Jiri Slaby <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
 Emil Kronborg <emil.kronborg@...tonmail.com>, Shawn Guo
 <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Uwe Kleine-König <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>, NXP Linux Team <linux-imx@....com>,
 "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 2/2] serial: mxs-auart: fix tx

On 01. 02. 24, 11:55, Jiri Slaby (SUSE) wrote:
> Emil reports:
>    After updating Linux on an i.MX28 board, serial communication over
>    AUART broke. When I TX from the board and measure on the TX pin, it
>    seems like the HW fifo is not emptied before the transmission is
>    stopped.
> 
> MXS performs weird things with stop_tx(). The driver makes it
> conditional on uart_tx_stopped().
> 
> So the driver needs special handling. Pass the brand new UART_TX_NOSTOP
> to uart_port_tx_flags() and handle the stop on its own.
> 
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
> Reported-by: Emil Kronborg <emil.kronborg@...tonmail.com>
> Fixes: 2d141e683e9a ("tty: serial: use uart_port_tx() helper")
> Closes: https://lore.kernel.org/all/miwgbnvy3hjpnricubg76ytpn7xoceehwahupy25bubbduu23s@om2lptpa26xw/

Am I unable to send a proper patch anymore?

I forgot to add mxs+arm maintainers:
Cc: Shawn Guo <shawnguo@...nel.org>
Cc: Sascha Hauer <s.hauer@...gutronix.de>
Cc: Pengutronix Kernel Team <kernel@...gutronix.de>
Cc: Fabio Estevam <festevam@...il.com>
Cc: NXP Linux Team <linux-imx@....com>
Cc: linux-arm-kernel@...ts.infradead.org

I can resend with those fixed, if you prefer...

> ---
>   drivers/tty/serial/mxs-auart.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> index 3ec725555bcc..4749331fe618 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -605,13 +605,16 @@ static void mxs_auart_tx_chars(struct mxs_auart_port *s)
>   		return;
>   	}
>   
> -	pending = uart_port_tx(&s->port, ch,
> +	pending = uart_port_tx_flags(&s->port, ch, UART_TX_NOSTOP,
>   		!(mxs_read(s, REG_STAT) & AUART_STAT_TXFF),
>   		mxs_write(ch, s, REG_DATA));
>   	if (pending)
>   		mxs_set(AUART_INTR_TXIEN, s, REG_INTR);
>   	else
>   		mxs_clr(AUART_INTR_TXIEN, s, REG_INTR);
> +
> +	if (uart_tx_stopped(&s->port))
> +               mxs_auart_stop_tx(&s->port);
>   }
>   
>   static void mxs_auart_rx_char(struct mxs_auart_port *s)

-- 
js
suse labs