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Subject[PATCH 2/2] serial: 8250: handle __start_tx() call in start_tx()
Date
As either start_tx_rs485() or start_tx() calls __start_tx() as the last
line of their logic, it makes sense to just move that call into
start_tx(). When start_tx_rs485() wants to defer tx using timer, return
false so start_tx() can return based on it.

Reorganize em485 code in serial8250_start_tx() so that the return can be
shared for the cases where tx start is deferred.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
drivers/tty/serial/8250/8250_port.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 448cfbb05f63..a3ffbdfe8fae 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1610,7 +1610,8 @@ void serial8250_em485_start_tx(struct uart_8250_port *up)
}
EXPORT_SYMBOL_GPL(serial8250_em485_start_tx);

-static inline void start_tx_rs485(struct uart_port *port)
+/* Returns false, if start_tx_timer was setup to defer TX start */
+static bool start_tx_rs485(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
struct uart_8250_em485 *em485 = up->em485;
@@ -1638,11 +1639,11 @@ static inline void start_tx_rs485(struct uart_port *port)
em485->active_timer = &em485->start_tx_timer;
start_hrtimer_ms(&em485->start_tx_timer,
up->port.rs485.delay_rts_before_send);
- return;
+ return false;
}
}

- __start_tx(port);
+ return true;
}

static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t)
@@ -1672,14 +1673,12 @@ static void serial8250_start_tx(struct uart_port *port)

serial8250_rpm_get_tx(up);

- if (em485 &&
- em485->active_timer == &em485->start_tx_timer)
- return;
-
- if (em485)
- start_tx_rs485(port);
- else
- __start_tx(port);
+ if (em485) {
+ if ((em485->active_timer == &em485->start_tx_timer) ||
+ !start_tx_rs485(port))
+ return;
+ }
+ __start_tx(port);
}

static void serial8250_throttle(struct uart_port *port)
--
2.30.2
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