[PATCH RFC 2/2] HID: appletb-kdb: Replace system_wq with system_dfl_wq

[Marco Crivellari]

Currently the code enqueue work items using mod_delayed_work(), using
system_wq, the old per-CPU Workqueue.

The function end up calling __queue_delayed_work(), which set a global
timer that could fire anywhere, enqueuing the work where the timer fired.

Unbound works could benefit from scheduler task placement, to optimize
performance and power consumption.

Since the workqueue work doesn't rely on per-cpu variables, there is no
obvious reason that justify the use of a per-cpu workqueue. So change the
workqueue with the new unbound version, system_dfl_wq.

Signed-off-by: Marco Crivellari <marco.crivellari@xxxxxxxx>
---
 drivers/hid/hid-appletb-kbd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-appletb-kbd.c b/drivers/hid/hid-appletb-kbd.c
index 462010a75899..5cc27066f602 100644
--- a/drivers/hid/hid-appletb-kbd.c
+++ b/drivers/hid/hid-appletb-kbd.c
@@ -175,7 +175,7 @@ static void appletb_inactivity_work(struct work_struct *work)
 		if (!kbd->has_dimmed) {
 			backlight_device_set_brightness(kbd->backlight_dev, 1);
 			kbd->has_dimmed = true;
-			mod_delayed_work(system_wq, &kbd->inactivity_work,
+			mod_delayed_work(system_dfl_wq, &kbd->inactivity_work,
 					 secs_to_jiffies(appletb_tb_idle_timeout));
 		} else if (!kbd->has_turned_off) {
 			backlight_device_set_brightness(kbd->backlight_dev, 0);
@@ -201,7 +201,7 @@ static void reset_inactivity_timer(struct appletb_kbd *kbd)
 			kbd->has_turned_off = false;
 			schedule_work(&kbd->restore_brightness_work);
 		}
-		mod_delayed_work(system_wq, &kbd->inactivity_work,
+		mod_delayed_work(system_dfl_wq, &kbd->inactivity_work,
 				 secs_to_jiffies(appletb_tb_dim_timeout));
 	}
 }
@@ -423,7 +423,7 @@ static int appletb_kbd_probe(struct hid_device *hdev, const struct hid_device_id
 		INIT_DELAYED_WORK(&kbd->inactivity_work, appletb_inactivity_work);
 		INIT_WORK(&kbd->restore_brightness_work,
 			  appletb_restore_brightness_work);
-		mod_delayed_work(system_wq, &kbd->inactivity_work,
+		mod_delayed_work(system_dfl_wq, &kbd->inactivity_work,
 				 secs_to_jiffies(appletb_tb_dim_timeout));
 	}
 
-- 
2.54.0