serial: core: Fix regression when runtime PM is not enabled

Commit 45a3a8ef8129 ("serial: core: Revert checks for tx runtime PM state")
caused a regression for Sun Ultra 60 for the sunsab driver as reported by
Nick Bowler <nbowler@draconx.ca>.

We need to add back the check runtime PM enabled state for serial port
controller device, I wrongly assumed earlier we could just remove it.

Fixes: 45a3a8ef8129 ("serial: core: Revert checks for tx runtime PM state")
Cc: stable <stable@kernel.org>
Reported-by: Nick Bowler <nbowler@draconx.ca>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20240325071649.27040-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index ff85ebd3a007dba0105e38d732efc0f6a6f8ab5b..25a83820927a53d9deb35a6fd17b09907bffe70e 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -156,7 +156,7 @@ static void __uart_start(struct uart_state *state)
         * enabled, serial_port_runtime_resume() calls start_tx() again
         * after enabling the device.
         */
-       if (pm_runtime_active(&port_dev->dev))
+       if (!pm_runtime_enabled(port->dev) || pm_runtime_active(&port_dev->dev))
                port->ops->start_tx(port);
        pm_runtime_mark_last_busy(&port_dev->dev);
        pm_runtime_put_autosuspend(&port_dev->dev);