linux-kernel - [RFC PATCH v1 1/1] leds: support to use own workqueue for each LED

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Date:   Sun, 30 Oct 2022 06:07:05 +0000
From:   Arseniy Krasnov <AVKrasnov@...rdevices.ru>
To:     Pavel Machek <pavel@....cz>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
        kernel <kernel@...rdevices.ru>
Subject: [RFC PATCH v1 1/1] leds: support to use own workqueue for each LED

This allows to set own workqueue for each LED. This may be useful, because
default 'system_wq' does not guarantee execution order of each work_struct,
thus for several brightness update requests (for multiple leds), real
brightness switch could be in random order.

Signed-off-by: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
---
 drivers/leds/led-core.c | 8 ++++++--
 include/linux/leds.h    | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 4a97cb745788..e8ecf332793a 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -188,6 +188,9 @@ static void led_blink_setup(struct led_classdev *led_cdev,
 
 void led_init_core(struct led_classdev *led_cdev)
 {
+	if (!led_cdev->set_brightness_wq)
+		led_cdev->set_brightness_wq = system_wq;
+
 	INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 
 	timer_setup(&led_cdev->blink_timer, led_timer_function, 0);
@@ -252,7 +255,8 @@ void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness)
 		 */
 		if (!brightness) {
 			set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);
-			schedule_work(&led_cdev->set_brightness_work);
+			queue_work(led_cdev->set_brightness_wq,
+				   &led_cdev->set_brightness_work);
 		} else {
 			set_bit(LED_BLINK_BRIGHTNESS_CHANGE,
 				&led_cdev->work_flags);
@@ -273,7 +277,7 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev, unsigned int value)
 
 	/* If brightness setting can sleep, delegate it to a work queue task */
 	led_cdev->delayed_set_value = value;
-	schedule_work(&led_cdev->set_brightness_work);
+	queue_work(led_cdev->set_brightness_wq, &led_cdev->set_brightness_work);
 }
 EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
 
diff --git a/include/linux/leds.h b/include/linux/leds.h
index ba4861ec73d3..1121bae21fed 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -140,6 +140,7 @@ struct led_classdev {
 	void			(*flash_resume)(struct led_classdev *led_cdev);
 
 	struct work_struct	set_brightness_work;
+	struct workqueue_struct *set_brightness_wq;
 	int			delayed_set_value;
 
 #ifdef CONFIG_LEDS_TRIGGERS
-- 
2.35.0