Re: [PATCH v3 1/9] serial: core: move RS485 configuration tasks from drivers into core

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On 22. 02. 22, 7:51, Jiri Slaby wrote:
On 22. 02. 22, 2:14, 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.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@xxxxxx>
---
  drivers/tty/serial/serial_core.c | 29 +++++++++++++++++++++++++++++
  1 file changed, 29 insertions(+)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 846192a7b4bf..2b3afe038c1c 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 +1287,32 @@ 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)) {
+        pr_warn("invalid RTS setting, using RTS_ON_SEND instead\n");

Can't we have a device prefix here, so that everyone knows what device is affected? Without that, it's not that useful. At least port->name & port->line could be printed. The uart core uses dev_* prints, but prints also line as uport->dev can be NULL sometimes.

And this comes from userspace, so should be ratelimited.

--
js
suse labs



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