Subject: [PATCH] RS485: fix inconsistencies in the meaning of some variables

From: [email-masked] (Claudio Scordino)
Date: Wed, 09 Nov 2011 15:51:49 +0100

Il 08/11/2011 15:24, Greg KH ha scritto:
> On Tue, Nov 08, 2011 at 01:48:04PM +0000, Alan Cox wrote:
>>> The modifications that I have proposed are very minimal, and most
>>> user-space code should continue to work without any difference. Any Cris
>>> user-space code will continue to work, because we didn't change the
>>> behavior of the driver. For Atmel user-space code, instead, the behavior
>>> of the driver changes only if flags are not set and delay variables
>>> contain a value different than 0 (which, hopefully, is not a very common
>>> situation). That's the reason why I preferred to not change the names of
>>> the variables, even if better names would be desirable.
>>
>> We have inconsistency between implementations. We don't have a change in
>> implementation. There isn't any way to resolve that except by fixing the
>> deviating implementation and doing it promptly.
>>
>> With my tty hat on I'm quite happy with this patch. The sooner it is
>> upstream the better.
> 
> Ok, I'll push to get it to Linus for the next rc release.

Hi Greg,

	in case you didn't push it yet, this is the patch with also the ack by Jesper.

Best regards,

	Claudio

Subject: RS485: fix inconsistencies in the meaning of some variables
From: Claudio Scordino <[email-masked]>

The crisv10.c and the atmel_serial.c serial drivers intepret the fields of the
serial_rs485 structure in a different way.
In particular, crisv10.c uses SER_RS485_RTS_AFTER_SEND and 
SER_RS485_RTS_ON_SEND for the voltage of the RTS pin; atmel_serial.c, instead,
uses these values to know if a delay must be set before and after sending.
This patch makes the usage of these variables consistent across all drivers and
fixes the Documentation as well.
>>From now on, SER_RS485_RTS_AFTER_SEND and SER_RS485_RTS_ON_SEND will be used to
set the voltage of the RTS pin (as in the crisv10.c driver); the delay will be
understood by looking only at the value of delay_rts_before_send and 
delay_rts_after_send.

Signed-off-by: Claudio Scordino <[email-masked]>
Signed-off-by: Darron Black <[email-masked]>
Acked-by: Jesper Nilsson <[email-masked]>
---
 Documentation/serial/serial-rs485.txt |   14 +++++++++++---
 drivers/tty/serial/atmel_serial.c     |   16 +++-------------
 drivers/tty/serial/crisv10.c          |   10 ++--------
 include/linux/serial.h                |   14 ++++++++------
 4 files changed, 24 insertions(+), 30 deletions(-)

diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt
index 079cb3d..41c8378 100644
--- a/Documentation/serial/serial-rs485.txt
+++ b/Documentation/serial/serial-rs485.txt
@@ -97,15 +97,23 @@
 
 	struct serial_rs485 rs485conf;
 
-	/* Set RS485 mode: */
+	/* Enable RS485 mode: */
 	rs485conf.flags |= SER_RS485_ENABLED;
 
+	/* Set logical level for RTS pin equal to 1 when sending: */
+	rs485conf.flags |= SER_RS485_RTS_ON_SEND;
+	/* or, set logical level for RTS pin equal to 0 when sending: */
+	rs485conf.flags &= ~(SER_RS485_RTS_ON_SEND);
+
+	/* Set logical level for RTS pin equal to 1 after sending: */
+	rs485conf.flags |= SER_RS485_RTS_AFTER_SEND;
+	/* or, set logical level for RTS pin equal to 0 after sending: */
+	rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);
+
 	/* Set rts delay before send, if needed: */
-	rs485conf.flags |= SER_RS485_RTS_BEFORE_SEND;
 	rs485conf.delay_rts_before_send = ...;
 
 	/* Set rts delay after send, if needed: */
-	rs485conf.flags |= SER_RS485_RTS_AFTER_SEND;
 	rs485conf.delay_rts_after_send = ...;
 
 	/* Set this flag if you want to receive data even whilst sending data */
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 4a0f86f..4c823f3 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -228,7 +228,7 @@ void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
 	if (rs485conf->flags & SER_RS485_ENABLED) {
 		dev_dbg(port->dev, "Setting UART to RS485\n");
 		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
-		if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND)
+		if ((rs485conf->delay_rts_after_send) > 0)
 			UART_PUT_TTGR(port, rs485conf->delay_rts_after_send);
 		mode |= ATMEL_US_USMODE_RS485;
 	} else {
@@ -304,7 +304,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 
 	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
 		dev_dbg(port->dev, "Setting UART to RS485\n");
-		if (atmel_port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
+		if ((atmel_port->rs485.delay_rts_after_send) > 0)
 			UART_PUT_TTGR(port,
 					atmel_port->rs485.delay_rts_after_send);
 		mode |= ATMEL_US_USMODE_RS485;
@@ -1228,7 +1228,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 
 	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
 		dev_dbg(port->dev, "Setting UART to RS485\n");
-		if (atmel_port->rs485.flags & SER_RS485_RTS_AFTER_SEND)
+		if ((atmel_port->rs485.delay_rts_after_send) > 0)
 			UART_PUT_TTGR(port,
 					atmel_port->rs485.delay_rts_after_send);
 		mode |= ATMEL_US_USMODE_RS485;
@@ -1447,16 +1447,6 @@ static void __devinit atmel_of_init_port(struct atmel_uart_port *atmel_port,
 		rs485conf->delay_rts_after_send = rs485_delay[1];
 		rs485conf->flags = 0;
 
-		if (rs485conf->delay_rts_before_send == 0 &&
-		    rs485conf->delay_rts_after_send == 0) {
-			rs485conf->flags |= SER_RS485_RTS_ON_SEND;
-		} else {
-			if (rs485conf->delay_rts_before_send)
-				rs485conf->flags |= SER_RS485_RTS_BEFORE_SEND;
-			if (rs485conf->delay_rts_after_send)
-				rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
-		}
-
 		if (of_get_property(np, "rs485-rx-during-tx", NULL))
 			rs485conf->flags |= SER_RS485_RX_DURING_TX;
 
diff --git a/drivers/tty/serial/crisv10.c b/drivers/tty/serial/crisv10.c
index b743504..1dfba7b 100644
--- a/drivers/tty/serial/crisv10.c
+++ b/drivers/tty/serial/crisv10.c
@@ -3234,9 +3234,8 @@ rs_write(struct tty_struct *tty,
 		e100_disable_rx(info);
 		e100_enable_rx_irq(info);
 #endif
-		if ((info->rs485.flags & SER_RS485_RTS_BEFORE_SEND) &&
-			(info->rs485.delay_rts_before_send > 0))
-				msleep(info->rs485.delay_rts_before_send);
+		if (info->rs485.delay_rts_before_send > 0)
+			msleep(info->rs485.delay_rts_before_send);
 	}
 #endif /* CONFIG_ETRAX_RS485 */
 
@@ -3693,10 +3692,6 @@ rs_ioctl(struct tty_struct *tty,
 
 		rs485data.delay_rts_before_send = rs485ctrl.delay_rts_before_send;
 		rs485data.flags = 0;
-		if (rs485data.delay_rts_before_send != 0)
-			rs485data.flags |= SER_RS485_RTS_BEFORE_SEND;
-		else
-			rs485data.flags &= ~(SER_RS485_RTS_BEFORE_SEND);
 
 		if (rs485ctrl.enabled)
 			rs485data.flags |= SER_RS485_ENABLED;
@@ -4531,7 +4526,6 @@ static int __init rs_init(void)
 		/* Set sane defaults */
 		info->rs485.flags &= ~(SER_RS485_RTS_ON_SEND);
 		info->rs485.flags |= SER_RS485_RTS_AFTER_SEND;
-		info->rs485.flags &= ~(SER_RS485_RTS_BEFORE_SEND);
 		info->rs485.delay_rts_before_send = 0;
 		info->rs485.flags &= ~(SER_RS485_ENABLED);
 #endif
diff --git a/include/linux/serial.h b/include/linux/serial.h
index 97ff8e2..3d86517 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -207,13 +207,15 @@ struct serial_icounter_struct {
 
 struct serial_rs485 {
 	__u32	flags;			/* RS485 feature flags */
-#define SER_RS485_ENABLED		(1 << 0)
-#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_ENABLED		(1 << 0)	/* If enabled */
+#define SER_RS485_RTS_ON_SEND		(1 << 1)	/* Logical level for
+							   RTS pin when
+							   sending */
+#define SER_RS485_RTS_AFTER_SEND	(1 << 2)	/* Logical level for
+							   RTS pin after sent*/
 #define SER_RS485_RX_DURING_TX		(1 << 4)
-	__u32	delay_rts_before_send;	/* Milliseconds */
-	__u32	delay_rts_after_send;	/* Milliseconds */
+	__u32	delay_rts_before_send;	/* Delay before send (milliseconds) */
+	__u32	delay_rts_after_send;	/* Delay after send (milliseconds) */
 	__u32	padding[5];		/* Memory is cheap, new structs
 					   are a royal PITA .. */
 };
-- 
1.7.1