linux-kernel - [PATCH] leds: Ensure hardware blinking turns off when requested

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Message-Id: <20220520171134.31415-1-eajames@linux.ibm.com>
Date:   Fri, 20 May 2022 12:11:34 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     pavel@....cz
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        eajames@...ux.ibm.com
Subject: [PATCH] leds: Ensure hardware blinking turns off when requested

If an LED is blinking through the hardware and the trigger is deactivated,
the driver will set the brightness to 0 to disable blinking. However, if
the LED driver doesn't support non-blocking operations, the request for
setting brightness to 0 will get queued. Then if a user requests a new
non-zero brightness before the request for 0 brightness is executed, the
LED blinking will not get disabled since the brightness will simply be
updated.
Fix this by flushing the workqueue before updating the requested
brightness.

Fixes: 4d71a4a12b13 ("leds: Add support for setting brightness in a synchronous way")
Signed-off-by: Eddie James <eajames@...ux.ibm.com>
---
 drivers/leds/led-class.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 6a8ea94834fa..861a1cb5df5b 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -55,6 +55,8 @@ static ssize_t brightness_store(struct device *dev,

 	if (state == LED_OFF)
 		led_trigger_remove(led_cdev);
+	/* flush out any request to disable blinking */
+	flush_work(&led_cdev->set_brightness_work);
 	led_set_brightness(led_cdev, state);
 	flush_work(&led_cdev->set_brightness_work);

-- 
2.27.0