> >> Maybe it would be better to update the stop_rx and add parameter,
> >> whether it should/shouldn't enable the loopback ?
> >
> > Since *stop_rx is part of struct uart_ops I can not add an input argument to the function.
>
> You could add a wrapper function and make stop_tx call that one.
Ok, yes that is possible. Do you want me to do that change?
Best regards,
Rickard
________________________________________
From: Marek Vasut <marex@xxxxxxx>
Sent: Tuesday, February 20, 2024 7:52 AM
To: Rickard X Andersson; linux-serial@xxxxxxxxxxxxxxx; rickard314.andersson@xxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; linux-imx@xxxxxxx; martin.fuzzey@flowbird.group; Christoph Niedermaier
Cc: kernel
Subject: Re: [PATCH] tty: serial: imx: Fix broken RS485
On 2/20/24 07:07, Rickard X Andersson wrote:
> On Fri, Feb 16, 2024 at 4:17 PM Marek Vasut <marex@xxxxxxx> wrote:
>>
>> On 2/16/24 13:46, Rickard Andersson wrote:
>>> From: Rickard x Andersson <rickaran@xxxxxxxx>
>>>
>>> When about to transmit the function imx_uart_start_tx is called and in
>>> some RS485 configurations this function will call imx_uart_stop_rx. The
>>> problem is that imx_uart_stop_rx will enable loopback and when loopback
>>> is enabled transmitted data will just be looped to RX.
>>>
>>> This patch fixes the above problem by explicitly disabling loopback in
>>> the case described above.
>>>
>>> Signed-off-by: Rickard x Andersson <rickaran@xxxxxxxx>
>>
>> Fixes: tag is missing.
>
> Ok, I will add.
>>
>>> ---
>>> drivers/tty/serial/imx.c | 9 ++++++++-
>>> 1 file changed, 8 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
>>> index 4aa72d5aeafb..899e331bdfc8 100644
>>> --- a/drivers/tty/serial/imx.c
>>> +++ b/drivers/tty/serial/imx.c
>>> @@ -683,8 +683,15 @@ static void imx_uart_start_tx(struct uart_port *port)
>>> imx_uart_writel(sport, ucr2, UCR2);
>>>
>>> if (!(port->rs485.flags & SER_RS485_RX_DURING_TX) &&
>>> - !port->rs485_rx_during_tx_gpio)
>>> + !port->rs485_rx_during_tx_gpio) {
>>> imx_uart_stop_rx(port);
>>> + /*
>>> + * The function imx_uart_stop_rx right above
>>> + * will enable loopback, but since we are just
>>> + * about to transmit then disable loopback.
>>> + */
>>> + imx_uart_disable_loopback_rs485(sport);
>>> + }
>>
>> Maybe it would be better to update the stop_rx and add parameter,
>> whether it should/shouldn't enable the loopback ?
>
> Since *stop_rx is part of struct uart_ops I can not add an input argument to the function.
You could add a wrapper function and make stop_tx call that one.
