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

From: [email-masked] (Nicolas Ferre)
Date: Mon, 14 Nov 2011 13:18:25 +0100

On 11/09/2011 03:51 PM, Claudio Scordino :
> 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]>

Surely too late, but I add it for the record:

Acked-by: Nicolas Ferre <[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 .. */
>  };

-- 
Nicolas Ferre