чт, 4 окт. 2018 г. в 11:55, Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>:
>
> On Thu, Oct 04, 2018 at 09:23:16AM +0200, Uwe Kleine-König wrote:
> > serial8250_tx_chars() is called from several places and the callers don't
> > consider that sending might not be allowed yet because the
> > rts_before_send delay isn't over yet.
> >
> > So teach serial8250_tx_chars() about rts_before_send and delay the
> > request accordingly if required.
> >
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> > ---
> > Cc: Tomas Melin <tomas.melin@xxxxxxxxxxx>
> > Cc: Daniel Golle <daniel@xxxxxxxxxxxxxx>
> > Cc: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx>
> > Cc: Lukas Wunner <lukas@xxxxxxxxx>
> > Cc: Aaron Sierra <asierra@xxxxxxxxxxx>
> > Cc: Rafael Gago <rafael.gago@xxxxxxxxx>
> > Cc: Daniel Jedrychowski <avistel@xxxxxxxxx>
> >
> > Hello,
> >
> > on a powerpc (MPC8313) this patch prevents sending characters too early
> > after an edge on CTS is detected. As the 8250 driver is quite "advanced"
> > I'd welcome testing feedback for other chip variants, so I added a few
> > people to Cc who did rs485 stuff in the past.
>
> You pretty much missed the author of contribution of RS485 emulation
> to 8250 driver.
>
> Cc'ed to Matwey.
I still don't understand the following. The only one user for this
code is 8250_omap which is armv7l. Where did MPC8313 came from?
>
> >
> > drivers/tty/serial/8250/8250_port.c | 31 +++++++++++++++++++++++++++--
> > 1 file changed, 29 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> > index 3f779d25ec0c..d8d7456f8ec3 100644
> > --- a/drivers/tty/serial/8250/8250_port.c
> > +++ b/drivers/tty/serial/8250/8250_port.c
> > @@ -1548,6 +1548,8 @@ static void serial8250_stop_tx(struct uart_port *port)
> > serial8250_rpm_put(up);
> > }
> >
> > +static void __serial8250_tx_chars(struct uart_8250_port *up);
> > +
> > static inline void __start_tx(struct uart_port *port)
> > {
> > struct uart_8250_port *up = up_to_u8250p(port);
> > @@ -1565,7 +1567,7 @@ static inline void __start_tx(struct uart_port *port)
> > lsr = serial_in(up, UART_LSR);
> > up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
> > if (lsr & UART_LSR_THRE)
> > - serial8250_tx_chars(up);
> > + __serial8250_tx_chars(up);
> > }
> > }
> >
> > @@ -1765,7 +1767,7 @@ unsigned char serial8250_rx_chars(struct uart_8250_port *up, unsigned char lsr)
> > }
> > EXPORT_SYMBOL_GPL(serial8250_rx_chars);
> >
> > -void serial8250_tx_chars(struct uart_8250_port *up)
> > +static void __serial8250_tx_chars(struct uart_8250_port *up)
> > {
> > struct uart_port *port = &up->port;
> > struct circ_buf *xmit = &port->state->xmit;
> > @@ -1813,6 +1815,31 @@ void serial8250_tx_chars(struct uart_8250_port *up)
> > if (uart_circ_empty(xmit) && !(up->capabilities & UART_CAP_RPM))
> > __stop_tx(up);
> > }
> > +
> > +/* called with port->lock taken and irqs off */
> > +void serial8250_tx_chars(struct uart_8250_port *up)
> > +{
> > + struct uart_8250_em485 *em485;
> > +
> > + em485 = up->em485;
> > + if (em485) {
> > + if (em485->active_timer == &em485->start_tx_timer)
> > + /*
> > + * Still waiting for rts_before_send delay. When the
> > + * timer triggers it will start tx.
> > + */
> > + return;
> > +
> > + /*
> > + * tx might have finshed before and the driver waits for
> > + * rts_after_send. Now as there is new data to be sent this
> > + * is void.
> > + */
> > + em485->active_timer = NULL;
> > + }
> > +
> > + __serial8250_tx_chars(up);
> > +}
> > EXPORT_SYMBOL_GPL(serial8250_tx_chars);
> >
> > /* Caller holds uart port lock */
> > --
> > 2.19.0
> >
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
--
With best regards,
Matwey V. Kornilov.
Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia
119234, Moscow, Universitetsky pr-k 13, +7 (495) 9392382
