2022-02-28 03:15:19

by Lino Sanfilippo

Subject: [PATCH v4 1/9] serial: core: move RS485 configuration tasks from drivers into core

Several drivers that support setting the RS485 configuration via userspace
implement one or more of the following tasks:

- in case of an invalid RTS configuration (both RTS after send and RTS on
send set or both unset) fall back to enable RTS on send and disable RTS
after send

- nullify the padding field of the returned serial_rs485 struct

- copy the configuration into the uart port struct

- limit RTS delays to 100 ms

Move these tasks into the serial core to make them generic and to provide
a consistent behaviour among all drivers.

Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/tty/serial/serial_core.c | 33 ++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 846192a7b4bf..06eb3cfbe610 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -42,6 +42,11 @@ static struct lock_class_key port_lock_key;

#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)

+/*
+ * Max time with active RTS before/after data is sent.
+ */
+#define RS485_MAX_RTS_DELAY 100 /* msecs */
+
static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
struct ktermios *old_termios);
static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
@@ -1282,8 +1287,36 @@ static int uart_set_rs485_config(struct uart_port *port,
if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
return -EFAULT;

+ /* pick sane settings if the user hasn't */
+ if (!(rs485.flags & SER_RS485_RTS_ON_SEND) ==
+ !(rs485.flags & SER_RS485_RTS_AFTER_SEND)) {
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
+ port->name, port->line);
+ rs485.flags |= SER_RS485_RTS_ON_SEND;
+ rs485.flags &= ~SER_RS485_RTS_AFTER_SEND;
+ }
+
+ if (rs485.delay_rts_before_send > RS485_MAX_RTS_DELAY) {
+ rs485.delay_rts_before_send = RS485_MAX_RTS_DELAY;
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): RTS delay before sending clamped to %u ms\n",
+ port->name, port->line, rs485.delay_rts_before_send);
+ }
+
+ if (rs485.delay_rts_after_send > RS485_MAX_RTS_DELAY) {
+ rs485.delay_rts_after_send = RS485_MAX_RTS_DELAY;
+ dev_warn_ratelimited(port->dev,
+ "%s (%d): RTS delay after sending clamped to %u ms\n",
+ port->name, port->line, rs485.delay_rts_after_send);
+ }
+ /* Return clean padding area to userspace */
+ memset(rs485.padding, 0, sizeof(rs485.padding));
+
spin_lock_irqsave(&port->lock, flags);
ret = port->rs485_config(port, &rs485);
+ if (!ret)
+ port->rs485 = rs485;
spin_unlock_irqrestore(&port->lock, flags);
if (ret)
return ret;

base-commit: 71404f653cf7858fdbb81dd5419a8a4ac4ffa20c
--
2.35.1

2022-03-21 23:08:43

by Lino Sanfilippo

Subject: Re: [PATCH v4 1/9] serial: core: move RS485 configuration tasks from drivers into core

Hi Greg, Jiri,

On 28.02.22 at 03:39, Lino Sanfilippo wrote:
> Several drivers that support setting the RS485 configuration via userspace
> implement one or more of the following tasks:
>
> - in case of an invalid RTS configuration (both RTS after send and RTS on
> send set or both unset) fall back to enable RTS on send and disable RTS
> after send
>
> - nullify the padding field of the returned serial_rs485 struct
>
> - copy the configuration into the uart port struct
>
> - limit RTS delays to 100 ms
>
> Move these tasks into the serial core to make them generic and to provide
> a consistent behaviour among all drivers.
>

is this patch series mergeable now? Or is there anything else to do from my side?

Regards,
Lino