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Message-ID: <4E536536.3030004@evidence.eu.com>
Date: Tue, 23 Aug 2011 10:30:46 +0200
From: Claudio Scordino <claudio@...dence.eu.com>
To: Greg KH <greg@...ah.com>
CC: Bernhard Roth <br@...net.de>, nicolas.ferre@...el.com,
linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] atmel_serial: RS485: receiving enabled when sending data
Il 22/08/2011 23:18, Greg KH ha scritto:
> On Mon, Aug 15, 2011 at 04:28:15PM +0200, Bernhard Roth wrote:
>> Hello!
>>
>> By default the atmel_serial driver in RS485 mode disables receiving
>> data until all data in the send buffer has been sent. This flag
>> allows to receive data even whilst sending data. This is very useful
>> to
>>
>> - check if the data has been sent correctly over the RS485 bus
>> - assure that no collision happened
>> - check for short circuits/termination issues on the RS485 bus
>>
>> Usually this functionality is realized by hardware, wether
>> controlling the RX-Enable pin of the RS485 transceiver with RTS
>> (driver control signal) or pulling it LOW permanently. The present
>> atmel_serial driver makes this impossible, thus requiring following
>> patch.
>>
>> Usage example:
>>
>> struct serial_rs485 rs485;
>>
>> memset(&rs485, 0, sizeof(rs485));
>> rs485.flags = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX;
>> ioctl(fd, TIOCSRS485,&rs485);
>>
>>
>>
>>
>> atmel_serial: RS485: receiving enabled when sending data
>>
>> By default the atmel_serial driver in RS485 mode disables receiving
>> data until
>> all data in the send buffer has been sent. This flag allows to receive data
>> even whilst sending data.
>>
>> Signed-off-by: Bernhard Roth<br@...net.de>
>> Signed-off-by: Claudio Scordino<claudio@...dence.eu.com>
>> ---
>> drivers/tty/serial/atmel_serial.c | 17 ++++++++++-------
>> include/linux/serial.h | 1 +
>> 2 files changed, 11 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/tty/serial/atmel_serial.c
>> b/drivers/tty/serial/atmel_serial.c
>> index af9b781..5f6c745 100644
>> --- a/drivers/tty/serial/atmel_serial.c
>> +++ b/drivers/tty/serial/atmel_serial.c
>> @@ -339,8 +339,9 @@ static void atmel_stop_tx(struct uart_port *port)
>> /* Disable interrupts */
>> UART_PUT_IDR(port, atmel_port->tx_done_mask);
>>
>> - if (atmel_port->rs485.flags& SER_RS485_ENABLED)
>> - atmel_start_rx(port);
>> + if ((atmel_port->rs485.flags& SER_RS485_ENABLED)&&
>> + !(atmel_port->rs485.flags& SER_RS485_RX_DURING_TX))
>> + atmel_start_rx(port);
>
> Can you fix your email client to not strip patches of tabs and resend
> this so that I can apply it?
>
> thanks,
>
> greg k-h
Hi Greg,
please find below the patch with the right tabs.
Remind however that the main author of the patch is Bernhard, not me.
Best regards,
Claudio
atmel_serial: RS485: receiving enabled when sending data
By default the atmel_serial driver in RS485 mode disables receiving data until
all data in the send buffer has been sent. This flag allows to receive data
even whilst sending data.
Signed-off-by: Bernhard Roth <br@...net.de>
Signed-off-by: Claudio Scordino <claudio@...dence.eu.com>
---
drivers/tty/serial/atmel_serial.c | 17 ++++++++++-------
include/linux/serial.h | 1 +
2 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index af9b781..5f6c745 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -339,8 +339,9 @@ static void atmel_stop_tx(struct uart_port *port)
/* Disable interrupts */
UART_PUT_IDR(port, atmel_port->tx_done_mask);
- if (atmel_port->rs485.flags & SER_RS485_ENABLED)
- atmel_start_rx(port);
+ if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+ !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX))
+ atmel_start_rx(port);
}
/*
@@ -356,8 +357,9 @@ static void atmel_start_tx(struct uart_port *port)
really need this.*/
return;
- if (atmel_port->rs485.flags & SER_RS485_ENABLED)
- atmel_stop_rx(port);
+ if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+ !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX))
+ atmel_stop_rx(port);
/* re-enable PDC transmit */
UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
@@ -680,9 +682,10 @@ static void atmel_tx_dma(struct uart_port *port)
/* Enable interrupts */
UART_PUT_IER(port, atmel_port->tx_done_mask);
} else {
- if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
- /* DMA done, stop TX, start RX for RS485 */
- atmel_start_rx(port);
+ if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+ !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX)) {
+ /* DMA done, stop TX, start RX for RS485 */
+ atmel_start_rx(port);
}
}
diff --git a/include/linux/serial.h b/include/linux/serial.h
index ef91406..97ff8e2 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -211,6 +211,7 @@ struct serial_rs485 {
#define SER_RS485_RTS_ON_SEND (1 << 1)
#define SER_RS485_RTS_AFTER_SEND (1 << 2)
#define SER_RS485_RTS_BEFORE_SEND (1 << 3)
+#define SER_RS485_RX_DURING_TX (1 << 4)
__u32 delay_rts_before_send; /* Milliseconds */
__u32 delay_rts_after_send; /* Milliseconds */
__u32 padding[5]; /* Memory is cheap, new structs
--
1.7.1
--
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