linux-kernel - [PATCH] leds: core: Use blocking op for system suspend

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Message-Id: <20200701093541.14191-1-kai.heng.feng@canonical.com>
Date:   Wed,  1 Jul 2020 17:35:40 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     jacek.anaszewski@...il.com, pavel@....cz
Cc:     anthony.wong@...onical.com,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Dan Murphy <dmurphy@...com>,
        linux-leds@...r.kernel.org (open list:LED SUBSYSTEM),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] leds: core: Use blocking op for system suspend

Sometimes LED won't be turned off by LED_CORE_SUSPENDRESUME flag upon
system suspend.

led_set_brightness_nopm() uses schedule_work() to set LED brightness.
However, there's no guarantee that the scheduled work gets executed
because no one calls flush_scheduled_work().

As flush_scheduled_work() may affect other drivers' suspend routines,
take a more contained approach which uses blocking op to make sure the
LED gets turned off.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/leds/led-core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index f1f718dbe0f8..9a5bfcd7a704 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -269,6 +269,11 @@ EXPORT_SYMBOL_GPL(led_set_brightness);
 void led_set_brightness_nopm(struct led_classdev *led_cdev,
 			      enum led_brightness value)
 {
+
+	if (led_cdev->flags & LED_SUSPENDED &&
+	    !__led_set_brightness_blocking(led_cdev, value))
+		return;
+
 	/* Use brightness_set op if available, it is guaranteed not to sleep */
 	if (!__led_set_brightness(led_cdev, value))
 		return;
-- 
2.17.1