2016-03-24 08:05:21

by Yegor Yefremov

Subject: [PATCH v2] tty/serial/8250: fix RS485 half-duplex RX

From: Yegor Yefremov <[email protected]>

When in half-duplex mode RX will be disabled before TX, but not
enabled after deactivating transmitter. This patch enables
UART_IER_RLSI and UART_IER_RDI interrupts after TX is over.

Cc: Matwey V. Kornilov <[email protected]>
Signed-off-by: Yegor Yefremov <[email protected]>
Fixes: e490c9144cfa ("tty: Add software emulated RS485 support for 8250")
---
Changes:
v2: change subject and add 'Fixes' tag

drivers/tty/serial/8250/8250_port.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index e213da0..00ad263 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1403,9 +1403,18 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p)
/*
* Empty the RX FIFO, we are not interested in anything
* received during the half-duplex transmission.
+ * Enable previously disabled RX interrupts.
*/
- if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
+ if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
serial8250_clear_fifos(p);
+
+ serial8250_rpm_get(p);
+
+ p->ier |= UART_IER_RLSI | UART_IER_RDI;
+ serial_port_out(&p->port, UART_IER, p->ier);
+
+ serial8250_rpm_put(p);
+ }
}

static void serial8250_em485_handle_stop_tx(unsigned long arg)
--
2.1.4

2016-03-31 05:23:17

by Yegor Yefremov

Subject: Re: [PATCH v2] tty/serial/8250: fix RS485 half-duplex RX

On Thu, Mar 24, 2016 at 9:03 AM, <[email protected]> wrote:
> From: Yegor Yefremov <[email protected]>
>
> When in half-duplex mode RX will be disabled before TX, but not
> enabled after deactivating transmitter. This patch enables
> UART_IER_RLSI and UART_IER_RDI interrupts after TX is over.
>
> Cc: Matwey V. Kornilov <[email protected]>
> Signed-off-by: Yegor Yefremov <[email protected]>
> Fixes: e490c9144cfa ("tty: Add software emulated RS485 support for 8250")

Transferring from Acked-by from v1:

Acked-by: Matwey V. Kornilov <[email protected]>

> ---
> Changes:
> v2: change subject and add 'Fixes' tag
>
> drivers/tty/serial/8250/8250_port.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index e213da0..00ad263 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -1403,9 +1403,18 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p)
> /*
> * Empty the RX FIFO, we are not interested in anything
> * received during the half-duplex transmission.
> + * Enable previously disabled RX interrupts.
> */
> - if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
> + if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
> serial8250_clear_fifos(p);
> +
> + serial8250_rpm_get(p);
> +
> + p->ier |= UART_IER_RLSI | UART_IER_RDI;
> + serial_port_out(&p->port, UART_IER, p->ier);
> +
> + serial8250_rpm_put(p);
> + }
> }
>
> static void serial8250_em485_handle_stop_tx(unsigned long arg)
> --
> 2.1.4
>

2016-03-31 08:10:43

by Matwey V. Kornilov

Subject: Re: [PATCH v2] tty/serial/8250: fix RS485 half-duplex RX

2016-03-24 11:03 GMT+03:00 <[email protected]>:
> From: Yegor Yefremov <[email protected]>
>
> When in half-duplex mode RX will be disabled before TX, but not
> enabled after deactivating transmitter. This patch enables
> UART_IER_RLSI and UART_IER_RDI interrupts after TX is over.
>
> Cc: Matwey V. Kornilov <[email protected]>
> Signed-off-by: Yegor Yefremov <[email protected]>
> Fixes: e490c9144cfa ("tty: Add software emulated RS485 support for 8250")

Acked-by: Matwey V. Kornilov <[email protected]>

> ---
> Changes:
> v2: change subject and add 'Fixes' tag
>
> drivers/tty/serial/8250/8250_port.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index e213da0..00ad263 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -1403,9 +1403,18 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p)
> /*
> * Empty the RX FIFO, we are not interested in anything
> * received during the half-duplex transmission.
> + * Enable previously disabled RX interrupts.
> */
> - if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX))
> + if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
> serial8250_clear_fifos(p);
> +
> + serial8250_rpm_get(p);
> +
> + p->ier |= UART_IER_RLSI | UART_IER_RDI;
> + serial_port_out(&p->port, UART_IER, p->ier);
> +
> + serial8250_rpm_put(p);
> + }
> }
>
> static void serial8250_em485_handle_stop_tx(unsigned long arg)
> --
> 2.1.4
>



--
With best regards,
Matwey V. Kornilov.
Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia
119991, Moscow, Universitetsky pr-k 13, +7 (495) 9392382