[PATCH/RFC v2 1/5] leds: Use set_brightness_work for brightness_set ops that can sleep

From: Jacek Anaszewski
Date: Tue Jun 30 2015 - 10:00:49 EST

This patch rearranges the core LED subsystem code, so that it
now shifts the responsibility for using work queues from drivers,
in case their brightness_set ops can sleep, onto the LED core
Addition of two flags: LED_BRIGHTNESS_FAST and LED_BLINK_DISABLE
as well as new_brightness_value property to the struct led_classdev
allows for employing existing set_brightness_work to do the job.
The modifications allows also to get rid of brightness_set_sync op,
as flash LED devices can now be handled properly only basing on the
SET_BRIGHTNESS_SYNC flag.

Signed-off-by: Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx>
---
drivers/leds/led-class.c | 18 +++++++----
drivers/leds/led-core.c | 50 +++++++++++++++++------------
drivers/leds/leds.h | 41 +++++++++++++----------
drivers/leds/trigger/ledtrig-backlight.c | 8 ++---
drivers/leds/trigger/ledtrig-default-on.c | 2 +-
drivers/leds/trigger/ledtrig-gpio.c | 6 ++--
drivers/leds/trigger/ledtrig-heartbeat.c | 4 +--
drivers/leds/trigger/ledtrig-oneshot.c | 4 +--
drivers/leds/trigger/ledtrig-transient.c | 8 ++---
include/linux/leds.h | 9 ++----
10 files changed, 84 insertions(+), 66 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index beabfbc..07ccaeb 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -109,7 +109,7 @@ static void led_timer_function(unsigned long data)
unsigned long delay;

if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
- led_set_brightness_async(led_cdev, LED_OFF);
+ led_set_brightness_nosleep(led_cdev, LED_OFF);
return;
}

@@ -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;
@@ -137,7 +137,7 @@ static void led_timer_function(unsigned long data)
delay = led_cdev->blink_delay_off;
}

- led_set_brightness_async(led_cdev, brightness);
+ led_set_brightness_nosleep(led_cdev, brightness);

/* Return in next iteration if led is in one-shot mode and we are in
* the final blink state so that the led is toggled each 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(led_cdev, led_cdev->delayed_set_value);
}

/**
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 549de7e..0e13fb0 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -42,13 +42,14 @@ static void led_set_software_blink(struct led_classdev *led_cdev,

/* never on - just set to off */
if (!delay_on) {
- led_set_brightness_async(led_cdev, LED_OFF);
+ led_set_brightness_nosleep(led_cdev, LED_OFF);
return;
}

/* never off - just set to brightness */
if (!delay_off) {
- led_set_brightness_async(led_cdev, led_cdev->blink_brightness);
+ led_set_brightness_nosleep(led_cdev,
+ led_cdev->blink_brightness);
return;
}

@@ -117,27 +118,36 @@ EXPORT_SYMBOL_GPL(led_stop_software_blink);
void led_set_brightness(struct led_classdev *led_cdev,
enum led_brightness brightness)
{
- int ret = 0;
-
- /* delay brightness if soft-blink is active */
+ /*
+ * In case blinking is on delay brightness setting
+ * to 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);
- return;
+ 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;
+ } else {
+ /*
+ * Don't use work queue if brightness has to be set as quickly
+ * as possible or if this is fast LED.
+ */
+ if ((led_cdev->flags & SET_BRIGHTNESS_SYNC) ||
+ (led_cdev->flags & LED_BRIGHTNESS_FAST)) {
+ __led_set_brightness(led_cdev, brightness);
+ return;
+ }
}

- if (led_cdev->flags & SET_BRIGHTNESS_ASYNC) {
- led_set_brightness_async(led_cdev, brightness);
- return;
- } else if (led_cdev->flags & SET_BRIGHTNESS_SYNC)
- ret = led_set_brightness_sync(led_cdev, brightness);
- else
- ret = -EINVAL;
-
- if (ret < 0)
- dev_dbg(led_cdev->dev, "Setting LED brightness failed (%d)\n",
- ret);
+ led_cdev->delayed_set_value = brightness;
+ schedule_work(&led_cdev->set_brightness_work);
}
EXPORT_SYMBOL(led_set_brightness);

diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index bc89d7a..dd9dd9b 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -2,8 +2,10 @@
* LED Core
*
* Copyright 2005 Openedhand Ltd.
+ * Copyright 2014, 2015 Samsung Electronics Co., Ltd.
*
* Author: Richard Purdie <rpurdie@xxxxxxxxxxxxxx>
+ * Author: Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
@@ -16,27 +18,15 @@
#include <linux/rwsem.h>
#include <linux/leds.h>

-static inline void led_set_brightness_async(struct led_classdev *led_cdev,
+static inline void __led_set_brightness(struct led_classdev *led_cdev,
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);
-}
-
-static inline int led_set_brightness_sync(struct led_classdev *led_cdev,
- enum led_brightness value)
-{
- int ret = 0;
-
led_cdev->brightness = min(value, led_cdev->max_brightness);

- if (!(led_cdev->flags & LED_SUSPENDED))
- ret = led_cdev->brightness_set_sync(led_cdev,
- led_cdev->brightness);
- return ret;
+ if (led_cdev->flags & LED_SUSPENDED)
+ return;
+
+ led_cdev->brightness_set(led_cdev, led_cdev->brightness);
}

static inline int led_get_brightness(struct led_classdev *led_cdev)
@@ -44,6 +34,23 @@ static inline int led_get_brightness(struct led_classdev *led_cdev)
return led_cdev->brightness;
}

+static inline void led_set_brightness_nosleep(struct led_classdev *led_cdev,
+ enum led_brightness value)
+{
+ /*
+ * Delegate setting brightness to a work queue task only for slow LEDs
+ * as the FAST ones are guaranteed not to sleep while setting
+ * brightness.
+ */
+ if (!(led_cdev->flags & LED_BRIGHTNESS_FAST)) {
+ led_cdev->delayed_set_value = value;
+ schedule_work(&led_cdev->set_brightness_work);
+ return;
+ }
+
+ __led_set_brightness(led_cdev, value);
+}
+
void led_stop_software_blink(struct led_classdev *led_cdev);

extern struct rw_semaphore leds_list_lock;
diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
index 59eca17..1ca1f16 100644
--- a/drivers/leds/trigger/ledtrig-backlight.c
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -51,9 +51,9 @@ static int fb_notifier_callback(struct notifier_block *p,

if ((n->old_status == UNBLANK) ^ n->invert) {
n->brightness = led->brightness;
- led_set_brightness_async(led, LED_OFF);
+ led_set_brightness_nosleep(led, LED_OFF);
} else {
- led_set_brightness_async(led, n->brightness);
+ led_set_brightness_nosleep(led, n->brightness);
}

n->old_status = new_status;
@@ -89,9 +89,9 @@ static ssize_t bl_trig_invert_store(struct device *dev,

/* After inverting, we need to update the LED. */
if ((n->old_status == BLANK) ^ n->invert)
- led_set_brightness_async(led, LED_OFF);
+ led_set_brightness_nosleep(led, LED_OFF);
else
- led_set_brightness_async(led, n->brightness);
+ led_set_brightness_nosleep(led, n->brightness);

return num;
}
diff --git a/drivers/leds/trigger/ledtrig-default-on.c b/drivers/leds/trigger/ledtrig-default-on.c
index 6f38f88..ff455cb 100644
--- a/drivers/leds/trigger/ledtrig-default-on.c
+++ b/drivers/leds/trigger/ledtrig-default-on.c
@@ -19,7 +19,7 @@

static void defon_trig_activate(struct led_classdev *led_cdev)
{
- led_set_brightness_async(led_cdev, led_cdev->max_brightness);
+ led_set_brightness_nosleep(led_cdev, led_cdev->max_brightness);
}

static struct led_trigger defon_led_trigger = {
diff --git a/drivers/leds/trigger/ledtrig-gpio.c b/drivers/leds/trigger/ledtrig-gpio.c
index 4cc7040..51288a4 100644
--- a/drivers/leds/trigger/ledtrig-gpio.c
+++ b/drivers/leds/trigger/ledtrig-gpio.c
@@ -54,12 +54,12 @@ static void gpio_trig_work(struct work_struct *work)

if (tmp) {
if (gpio_data->desired_brightness)
- led_set_brightness_async(gpio_data->led,
+ led_set_brightness_nosleep(gpio_data->led,
gpio_data->desired_brightness);
else
- led_set_brightness_async(gpio_data->led, LED_FULL);
+ led_set_brightness_nosleep(gpio_data->led, LED_FULL);
} else {
- led_set_brightness_async(gpio_data->led, LED_OFF);
+ led_set_brightness_nosleep(gpio_data->led, LED_OFF);
}
}

diff --git a/drivers/leds/trigger/ledtrig-heartbeat.c b/drivers/leds/trigger/ledtrig-heartbeat.c
index fea6871..3dc6f0c 100644
--- a/drivers/leds/trigger/ledtrig-heartbeat.c
+++ b/drivers/leds/trigger/ledtrig-heartbeat.c
@@ -37,7 +37,7 @@ static void led_heartbeat_function(unsigned long data)
unsigned long delay = 0;

if (unlikely(panic_heartbeats)) {
- led_set_brightness(led_cdev, LED_OFF);
+ led_set_brightness_nosleep(led_cdev, LED_OFF);
return;
}

@@ -74,7 +74,7 @@ static void led_heartbeat_function(unsigned long data)
break;
}

- led_set_brightness_async(led_cdev, brightness);
+ led_set_brightness_nosleep(led_cdev, brightness);
mod_timer(&heartbeat_data->timer, jiffies + delay);
}

diff --git a/drivers/leds/trigger/ledtrig-oneshot.c b/drivers/leds/trigger/ledtrig-oneshot.c
index fbd02cd..6729317 100644
--- a/drivers/leds/trigger/ledtrig-oneshot.c
+++ b/drivers/leds/trigger/ledtrig-oneshot.c
@@ -63,9 +63,9 @@ static ssize_t led_invert_store(struct device *dev,
oneshot_data->invert = !!state;

if (oneshot_data->invert)
- led_set_brightness_async(led_cdev, LED_FULL);
+ led_set_brightness_nosleep(led_cdev, LED_FULL);
else
- led_set_brightness_async(led_cdev, LED_OFF);
+ led_set_brightness_nosleep(led_cdev, LED_OFF);

return size;
}
diff --git a/drivers/leds/trigger/ledtrig-transient.c b/drivers/leds/trigger/ledtrig-transient.c
index 3c34de4..1dddd8f 100644
--- a/drivers/leds/trigger/ledtrig-transient.c
+++ b/drivers/leds/trigger/ledtrig-transient.c
@@ -41,7 +41,7 @@ static void transient_timer_function(unsigned long data)
struct transient_trig_data *transient_data = led_cdev->trigger_data;

transient_data->activate = 0;
- led_set_brightness_async(led_cdev, transient_data->restore_state);
+ led_set_brightness_nosleep(led_cdev, transient_data->restore_state);
}

static ssize_t transient_activate_show(struct device *dev,
@@ -72,7 +72,7 @@ static ssize_t transient_activate_store(struct device *dev,
if (state == 0 && transient_data->activate == 1) {
del_timer(&transient_data->timer);
transient_data->activate = state;
- led_set_brightness_async(led_cdev,
+ led_set_brightness_nosleep(led_cdev,
transient_data->restore_state);
return size;
}
@@ -81,7 +81,7 @@ static ssize_t transient_activate_store(struct device *dev,
if (state == 1 && transient_data->activate == 0 &&
transient_data->duration != 0) {
transient_data->activate = state;
- led_set_brightness_async(led_cdev, transient_data->state);
+ led_set_brightness_nosleep(led_cdev, transient_data->state);
transient_data->restore_state =
(transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
mod_timer(&transient_data->timer,
@@ -204,7 +204,7 @@ static void transient_trig_deactivate(struct led_classdev *led_cdev)

if (led_cdev->activated) {
del_timer_sync(&transient_data->timer);
- led_set_brightness_async(led_cdev,
+ led_set_brightness_nosleep(led_cdev,
transient_data->restore_state);
device_remove_file(led_cdev->dev, &dev_attr_activate);
device_remove_file(led_cdev->dev, &dev_attr_duration);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index b122eea..ea99de9 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -48,17 +48,13 @@ struct led_classdev {
#define SET_BRIGHTNESS_ASYNC (1 << 21)
#define SET_BRIGHTNESS_SYNC (1 << 22)
#define LED_DEV_CAP_FLASH (1 << 23)
+#define LED_BRIGHTNESS_FAST (1 << 24)
+#define LED_BLINK_DISABLE (1 << 25)

/* Set LED brightness level */
/* Must not sleep, use a workqueue if needed */
void (*brightness_set)(struct led_classdev *led_cdev,
enum led_brightness brightness);
- /*
- * Set LED brightness level immediately - it can block the caller for
- * the time required for accessing a LED device register.
- */
- int (*brightness_set_sync)(struct led_classdev *led_cdev,
- enum led_brightness brightness);
/* Get LED brightness level */
enum led_brightness (*brightness_get)(struct led_classdev *led_cdev);

@@ -87,6 +83,7 @@ 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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/