We can use the prep_tx() call to wake up an idle serial port. This allows
ust to remove the depedency to pm_runtime_irq_safe() for 8250_omap driver
in the following patches.
Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_port.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1650,6 +1650,29 @@ static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t)
return HRTIMER_NORESTART;
}
+static int serial8250_prep_tx(struct uart_port *port)
+{
+ struct uart_8250_port *up = up_to_u8250p(port);
+ struct device *dev = up->port.dev;
+ int err;
+
+ if (!(up->capabilities & UART_CAP_RPM))
+ return 0;
+
+ if (!pm_runtime_suspended(dev)) {
+ pm_runtime_mark_last_busy(dev);
+ return 0;
+ }
+
+ err = pm_request_resume(dev);
+ if (err < 0) {
+ dev_warn(dev, "prep_tx wakeup failed: %d\n", err);
+ return err;
+ }
+
+ return -EINPROGRESS;
+}
+
static void serial8250_start_tx(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
@@ -3227,6 +3250,7 @@ static const struct uart_ops serial8250_pops = {
.set_mctrl = serial8250_set_mctrl,
.get_mctrl = serial8250_get_mctrl,
.stop_tx = serial8250_stop_tx,
+ .prep_tx = serial8250_prep_tx,
.start_tx = serial8250_start_tx,
.throttle = serial8250_throttle,
.unthrottle = serial8250_unthrottle,
--
2.33.0
