From: Jacek Anaszewski <j.anaszewski@samsung.com>
To: linux-leds@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, cooloney@gmail.com, rpurdie@rpsys.net,
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        sguinot@lacie.com, kyungmin.park@samsung.com,
        Jacek Anaszewski <j.anaszewski@samsung.com>
Subject: [PATCH/RFC v3 2/7] leds: Improve asynchronous path of setting
 brightness
Date: Fri, 03 Jul 2015 15:10:47 +0200
Message-id: <1435929052-8736-3-git-send-email-j.anaszewski@samsung.com>
In-reply-to: <1435929052-8736-1-git-send-email-j.anaszewski@samsung.com>
References: <1435929052-8736-1-git-send-email-j.anaszewski@samsung.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 4865
Lines: 138

led_set_brightness_async function didn't set the brightness in an
asynchronous way in all cases. It was mistakenly assuming that all
LED subsystem drivers use work queue in their brightness_set op,
whereas only half of them does that. Modify the function to assure
setting brightness asynchronously in all cases by using existing
set_brightness_delayed work queue.

The work queue is now made using led_set_brightness_sync for setting
brightness. This modification changes the initial purpose of the work
queue, which was used for setting brightness only if blink timer was
active. In order to keep this functionality a LED_BLINK_DISABLE flag
is being introduced, as well as a new 'new_brightness_value' field
is being added to the struct led_classdev. All these improvements
entail changes in the led_brightness_set function.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
---
 drivers/leds/led-class.c |   14 +++++++++-----
 drivers/leds/led-core.c  |   20 ++++++++++++++++----
 drivers/leds/leds.h      |    9 +++------
 include/linux/leds.h     |    2 ++
 4 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index beabfbc..b8decf7 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -121,10 +121,10 @@ static void led_timer_function(unsigned long data)
 	brightness = led_get_brightness(led_cdev);
 	if (!brightness) {
 		/* Time to switch the LED on. */
-		if (led_cdev->delayed_set_value) {
+		if (led_cdev->new_brightness_value) {
 			led_cdev->blink_brightness =
-					led_cdev->delayed_set_value;
-			led_cdev->delayed_set_value = 0;
+					led_cdev->new_brightness_value;
+			led_cdev->new_brightness_value = 0;
 		}
 		brightness = led_cdev->blink_brightness;
 		delay = led_cdev->blink_delay_on;
@@ -161,9 +161,13 @@ static void set_brightness_delayed(struct work_struct *ws)
 	struct led_classdev *led_cdev =
 		container_of(ws, struct led_classdev, set_brightness_work);
 
-	led_stop_software_blink(led_cdev);
+	if (led_cdev->flags & LED_BLINK_DISABLE) {
+		led_stop_software_blink(led_cdev);
+		led_cdev->flags &= ~LED_BLINK_DISABLE;
+		return;
+	}
 
-	led_set_brightness_async(led_cdev, led_cdev->delayed_set_value);
+	led_set_brightness_sync(led_cdev, led_cdev->delayed_set_value);
 }
 
 /**
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 549de7e..16fe995 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -119,11 +119,23 @@ void led_set_brightness(struct led_classdev *led_cdev,
 {
 	int ret = 0;
 
-	/* delay brightness if soft-blink is active */
+	/*
+	 * In case blinking is on delay brightness setting
+	 * until the next timer tick.
+	 */
 	if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
-		led_cdev->delayed_set_value = brightness;
-		if (brightness == LED_OFF)
-			schedule_work(&led_cdev->set_brightness_work);
+		led_cdev->new_brightness_value = brightness;
+
+		/* New brightness will be set on next timer tick. */
+		if (brightness != LED_OFF)
+			return;
+		/*
+		 * If need to disable soft blinking delegate this to the
+		 * work queue task to avoid problems in case we are
+		 * called from hard irq context.
+		 */
+		led_cdev->flags |= LED_BLINK_DISABLE;
+		led_set_brightness_async(led_cdev, brightness);
 		return;
 	}
 
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index 1c026c9..ca38f6a 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -17,13 +17,10 @@
 #include <linux/leds.h>
 
 static inline void led_set_brightness_async(struct led_classdev *led_cdev,
-					enum led_brightness value)
+					    enum led_brightness value)
 {
-	value = min(value, led_cdev->max_brightness);
-	led_cdev->brightness = value;
-
-	if (!(led_cdev->flags & LED_SUSPENDED))
-		led_cdev->brightness_set(led_cdev, value);
+	led_cdev->delayed_set_value = value;
+	schedule_work(&led_cdev->set_brightness_work);
 }
 
 static inline int led_get_brightness(struct led_classdev *led_cdev)
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 9b62a3c..bf4a938 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -48,6 +48,7 @@ struct led_classdev {
 #define SET_BRIGHTNESS_ASYNC	(1 << 21)
 #define SET_BRIGHTNESS_SYNC	(1 << 22)
 #define LED_DEV_CAP_FLASH	(1 << 23)
+#define LED_BLINK_DISABLE	(1 << 24)
 
 	/* Set LED brightness level */
 	/* Must not sleep, use a workqueue if needed */
@@ -87,6 +88,7 @@ struct led_classdev {
 
 	struct work_struct	set_brightness_work;
 	int			delayed_set_value;
+	int			new_brightness_value;
 
 #ifdef CONFIG_LEDS_TRIGGERS
 	/* Protects the trigger data below */
-- 
1.7.9.5

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