We want the serial device to be wakeup-capable but not actually enable
the wakeup function. The original code results in making the serial
device wakeup-capable, then enabling and then immediately disabling
the actual wakeup feature on the device. This ends up in a
synchronise_rcu() in wakeup_source_remove() which can take some 15ms
to run, yet is entirely avoidable. The cost over 4 ports is about 600ms
on my Tegra2x system (with CONFIG_PREEMPT disabled).
Using the new function avoids this problem.
Signed-off-by: Simon Glass <sjg@xxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index c7bf31a..a8b01db 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2348,11 +2348,11 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
*/
tty_dev = tty_register_device(drv->tty_driver, uport->line, uport->dev);
if (likely(!IS_ERR(tty_dev))) {
- device_init_wakeup(tty_dev, 1);
- device_set_wakeup_enable(tty_dev, 0);
- } else
+ device_init_wakeup_flag(tty_dev, PM_WAKEUP_CAP);
+ } else {
printk(KERN_ERR "Cannot register tty device on line %d\n",
uport->line);
+ }
/*
* Ensure UPF_DEAD is not set.
--
1.7.7.3
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