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Message-ID: <4EC10711.4050906@atmel.com>
Date: Mon, 14 Nov 2011 13:18:25 +0100
From: Nicolas Ferre <nicolas.ferre@...el.com>
To: Claudio Scordino <claudio@...dence.eu.com>,
Greg KH <greg@...ah.com>
CC: Alan Cox <alan@...rguk.ukuu.org.uk>, alan@...ux.intel.com,
linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Jesper Nilsson <Jesper.Nilsson@...s.com>,
Mikael Starvik <mikael.starvik@...s.com>,
Darron Black <darron@...ffin.net>
Subject: Re: [PATCH] RS485: fix inconsistencies in the meaning of some variables
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 <claudio@...dence.eu.com>
>
> 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 <claudio@...dence.eu.com>
> Signed-off-by: Darron Black <darron@...ffin.net>
> Acked-by: Jesper Nilsson <jesper.nilsson@...s.com>
Surely too late, but I add it for the record:
Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
> ---
> 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
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