From: nicolas.ferre@atmel•com (Nicolas Ferre)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] tty/serial: atmel: fix RS485 half duplex with DMA
Date: Mon, 13 Jun 2016 11:51:43 +0200 [thread overview]
Message-ID: <575E822F.7050501@atmel.com> (raw)
In-Reply-To: <57500D60.2000900@atmel.com>
Le 02/06/2016 12:41, Nicolas Ferre a ?crit :
> Le 28/05/2016 00:54, Alexandre Belloni a ?crit :
>> When using DMA, half duplex doesn't work properly because rx is not stopped
>> before starting tx. Ensure we call atmel_stop_rx() in the DMA case.
>>
>> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons•com>
>
> Acked-by: Nicolas Ferre <nicolas.ferre@atmel•com>
>
> We can also add:
> Cc: <stable@vger•kernel.org> # v4.3+
>
>
> Thanks Alexandre!
Greg,
It's not a regression but a good fix for this rs485 mode. So I suspect
it can still be queued for 4.7-rc... (aka: gentle ping).
Bye,
>> ---
>> drivers/tty/serial/atmel_serial.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
>> index 954941dd8124..f9c798cba83f 100644
>> --- a/drivers/tty/serial/atmel_serial.c
>> +++ b/drivers/tty/serial/atmel_serial.c
>> @@ -482,19 +482,21 @@ static void atmel_start_tx(struct uart_port *port)
>> {
>> struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>>
>> - if (atmel_use_pdc_tx(port)) {
>> - if (atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN)
>> - /* The transmitter is already running. Yes, we
>> - really need this.*/
>> - return;
>> + if (atmel_use_pdc_tx(port) && (atmel_uart_readl(port, ATMEL_PDC_PTSR)
>> + & ATMEL_PDC_TXTEN))
>> + /* The transmitter is already running. Yes, we
>> + really need this.*/
>> + return;
>>
>> + if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port))
>> if ((port->rs485.flags & SER_RS485_ENABLED) &&
>> !(port->rs485.flags & SER_RS485_RX_DURING_TX))
>> atmel_stop_rx(port);
>>
>> + if (atmel_use_pdc_tx(port))
>> /* re-enable PDC transmit */
>> atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);
>> - }
>> +
>> /* Enable interrupts */
>> atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);
>> }
>>
>
>
--
Nicolas Ferre
prev parent reply other threads:[~2016-06-13 9:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-27 22:54 [PATCH] tty/serial: atmel: fix RS485 half duplex with DMA Alexandre Belloni
2016-06-02 10:41 ` Nicolas Ferre
2016-06-13 9:51 ` Nicolas Ferre [this message]
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