[PATCH 1/2] tty: serial: imx: Only configure the wake register when device is set as wakeup source

[Sherry Sun <sherry.sun@nxp.com>]

Currently, imx uart defaults to enabling the wake related registers for
all uart devices. However, it is unnecessary for those devices not
configured as wakeup source, so add device_may_wakeup() check before
configuring the uart wake related registers.

Fixes: db1a9b55004c ("tty: serial: imx: Allow UART to be a source for wakeup")
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
---
 drivers/tty/serial/imx.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 500dfc009d03..4ddfc89816bf 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2697,7 +2697,22 @@ static void imx_uart_save_context(struct imx_port *sport)
 /* called with irq off */
 static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)
 {
+	struct tty_port *port = &sport->port.state->port;
+	struct tty_struct *tty;
+	struct device *tty_dev;
 	u32 ucr3;
+	bool may_wake;
+
+	tty = tty_port_tty_get(port);
+	if (tty) {
+		tty_dev = tty->dev;
+		may_wake = tty_dev && device_may_wakeup(tty_dev);
+		tty_kref_put(tty);
+	}
+
+	/* only configure the wake register when device set as wakeup source */
+	if (!may_wake)
+		return;
 
 	uart_port_lock_irq(&sport->port);
 
-- 
2.34.1