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    SubjectRe: [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@evidence.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@evidence.eu.com>
    > Signed-off-by: Darron Black <darron@griffin.net>
    > Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>

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

    Acked-by: Nicolas Ferre <nicolas.ferre@atmel.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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