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![Tony Makkiel](/assets/img/avatar_default.png)
Commit76931edd54
("leds: fix brightness changing when software blinking is active") changed the semantics of led_set_brightness() which according to the documentation should disable blinking upon any brightness setting. Moreover it made it different for soft blink case, where it was possible to change blink brightness, and for hardware blink case, where setting any brightness greater than 0 was ignored. While the change itself is against the documentation claims, it was driven also by the fact that timer trigger remained active after turning blinking off. Fixing that would have required major refactoring in the led-core, led-class, and led-triggers because of cyclic dependencies. Finally, it has been decided that allowing for brightness change during blinking is beneficial as it can be accomplished without disturbing blink rhythm. The change in brightness setting semantics will not affect existing LED class drivers that implement blink_set op thanks to the LED_BLINK_SW flag introduced by this patch. The flag state will be from now on checked in led_set_brightness() which will allow to distinguish between software and hardware blink mode. In the latter case the control will be passed directly to the drivers which apply their semantics on brightness set, which is disable the blinking in case of most such drivers. New drivers will apply new semantics and just change the brightness while hardware blinking is on, if possible. The issue was smuggled by subsequent LED core improvements, which modified the code that originally introduced the problem. Fixes:f1e80c0741
("leds: core: Add two new LED_BLINK_ flags") Signed-off-by: Tony Makkiel <tony.makkiel@daqri.com> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
327 lines
8.5 KiB
C
327 lines
8.5 KiB
C
/*
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* LED Class Core
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*
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* Copyright 2005-2006 Openedhand Ltd.
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*
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* Author: Richard Purdie <rpurdie@openedhand.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/leds.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/rwsem.h>
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#include "leds.h"
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DECLARE_RWSEM(leds_list_lock);
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EXPORT_SYMBOL_GPL(leds_list_lock);
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LIST_HEAD(leds_list);
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EXPORT_SYMBOL_GPL(leds_list);
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static int __led_set_brightness(struct led_classdev *led_cdev,
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enum led_brightness value)
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{
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if (!led_cdev->brightness_set)
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return -ENOTSUPP;
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led_cdev->brightness_set(led_cdev, value);
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return 0;
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}
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static int __led_set_brightness_blocking(struct led_classdev *led_cdev,
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enum led_brightness value)
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{
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if (!led_cdev->brightness_set_blocking)
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return -ENOTSUPP;
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return led_cdev->brightness_set_blocking(led_cdev, value);
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}
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static void led_timer_function(unsigned long data)
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{
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struct led_classdev *led_cdev = (void *)data;
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unsigned long brightness;
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unsigned long delay;
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if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
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led_set_brightness_nosleep(led_cdev, LED_OFF);
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led_cdev->flags &= ~LED_BLINK_SW;
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return;
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}
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if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
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led_cdev->flags &= ~(LED_BLINK_ONESHOT_STOP | LED_BLINK_SW);
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return;
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}
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brightness = led_get_brightness(led_cdev);
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if (!brightness) {
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/* Time to switch the LED on. */
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brightness = led_cdev->blink_brightness;
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delay = led_cdev->blink_delay_on;
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} else {
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/* Store the current brightness value to be able
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* to restore it when the delay_off period is over.
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* Do it only if there is no pending blink brightness
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* change, to avoid overwriting the new value.
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*/
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if (!(led_cdev->flags & LED_BLINK_BRIGHTNESS_CHANGE))
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led_cdev->blink_brightness = brightness;
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else
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led_cdev->flags &= ~LED_BLINK_BRIGHTNESS_CHANGE;
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brightness = LED_OFF;
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delay = led_cdev->blink_delay_off;
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}
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led_set_brightness_nosleep(led_cdev, brightness);
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/* Return in next iteration if led is in one-shot mode and we are in
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* the final blink state so that the led is toggled each delay_on +
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* delay_off milliseconds in worst case.
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*/
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if (led_cdev->flags & LED_BLINK_ONESHOT) {
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if (led_cdev->flags & LED_BLINK_INVERT) {
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if (brightness)
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led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
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} else {
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if (!brightness)
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led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
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}
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}
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mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
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}
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static void set_brightness_delayed(struct work_struct *ws)
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{
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struct led_classdev *led_cdev =
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container_of(ws, struct led_classdev, set_brightness_work);
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int ret = 0;
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if (led_cdev->flags & LED_BLINK_DISABLE) {
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led_cdev->delayed_set_value = LED_OFF;
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led_stop_software_blink(led_cdev);
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led_cdev->flags &= ~LED_BLINK_DISABLE;
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}
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ret = __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
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if (ret == -ENOTSUPP)
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ret = __led_set_brightness_blocking(led_cdev,
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led_cdev->delayed_set_value);
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if (ret < 0 &&
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/* LED HW might have been unplugged, therefore don't warn */
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!(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
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(led_cdev->flags & LED_HW_PLUGGABLE)))
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dev_err(led_cdev->dev,
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"Setting an LED's brightness failed (%d)\n", ret);
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}
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static void led_set_software_blink(struct led_classdev *led_cdev,
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unsigned long delay_on,
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unsigned long delay_off)
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{
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int current_brightness;
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current_brightness = led_get_brightness(led_cdev);
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if (current_brightness)
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led_cdev->blink_brightness = current_brightness;
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if (!led_cdev->blink_brightness)
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led_cdev->blink_brightness = led_cdev->max_brightness;
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led_cdev->blink_delay_on = delay_on;
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led_cdev->blink_delay_off = delay_off;
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/* never on - just set to off */
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if (!delay_on) {
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led_set_brightness_nosleep(led_cdev, LED_OFF);
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return;
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}
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/* never off - just set to brightness */
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if (!delay_off) {
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led_set_brightness_nosleep(led_cdev,
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led_cdev->blink_brightness);
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return;
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}
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led_cdev->flags |= LED_BLINK_SW;
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mod_timer(&led_cdev->blink_timer, jiffies + 1);
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}
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static void led_blink_setup(struct led_classdev *led_cdev,
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unsigned long *delay_on,
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unsigned long *delay_off)
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{
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if (!(led_cdev->flags & LED_BLINK_ONESHOT) &&
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led_cdev->blink_set &&
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!led_cdev->blink_set(led_cdev, delay_on, delay_off))
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return;
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/* blink with 1 Hz as default if nothing specified */
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if (!*delay_on && !*delay_off)
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*delay_on = *delay_off = 500;
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led_set_software_blink(led_cdev, *delay_on, *delay_off);
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}
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void led_init_core(struct led_classdev *led_cdev)
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{
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INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
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setup_timer(&led_cdev->blink_timer, led_timer_function,
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(unsigned long)led_cdev);
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}
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EXPORT_SYMBOL_GPL(led_init_core);
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void led_blink_set(struct led_classdev *led_cdev,
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unsigned long *delay_on,
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unsigned long *delay_off)
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{
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del_timer_sync(&led_cdev->blink_timer);
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led_cdev->flags &= ~LED_BLINK_ONESHOT;
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led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
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led_blink_setup(led_cdev, delay_on, delay_off);
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}
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EXPORT_SYMBOL_GPL(led_blink_set);
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void led_blink_set_oneshot(struct led_classdev *led_cdev,
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unsigned long *delay_on,
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unsigned long *delay_off,
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int invert)
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{
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if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
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timer_pending(&led_cdev->blink_timer))
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return;
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led_cdev->flags |= LED_BLINK_ONESHOT;
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led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
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if (invert)
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led_cdev->flags |= LED_BLINK_INVERT;
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else
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led_cdev->flags &= ~LED_BLINK_INVERT;
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led_blink_setup(led_cdev, delay_on, delay_off);
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}
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EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
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void led_stop_software_blink(struct led_classdev *led_cdev)
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{
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del_timer_sync(&led_cdev->blink_timer);
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led_cdev->blink_delay_on = 0;
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led_cdev->blink_delay_off = 0;
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led_cdev->flags &= ~LED_BLINK_SW;
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}
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EXPORT_SYMBOL_GPL(led_stop_software_blink);
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void led_set_brightness(struct led_classdev *led_cdev,
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enum led_brightness brightness)
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{
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/*
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* If software blink is active, delay brightness setting
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* until the next timer tick.
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*/
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if (led_cdev->flags & LED_BLINK_SW) {
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/*
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* If we need to disable soft blinking delegate this to the
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* work queue task to avoid problems in case we are called
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* from hard irq context.
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*/
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if (brightness == LED_OFF) {
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led_cdev->flags |= LED_BLINK_DISABLE;
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schedule_work(&led_cdev->set_brightness_work);
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} else {
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led_cdev->flags |= LED_BLINK_BRIGHTNESS_CHANGE;
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led_cdev->blink_brightness = brightness;
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}
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return;
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}
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led_set_brightness_nosleep(led_cdev, brightness);
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}
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EXPORT_SYMBOL_GPL(led_set_brightness);
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void led_set_brightness_nopm(struct led_classdev *led_cdev,
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enum led_brightness value)
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{
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/* Use brightness_set op if available, it is guaranteed not to sleep */
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if (!__led_set_brightness(led_cdev, value))
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return;
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/* If brightness setting can sleep, delegate it to a work queue task */
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led_cdev->delayed_set_value = value;
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schedule_work(&led_cdev->set_brightness_work);
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}
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EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
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void led_set_brightness_nosleep(struct led_classdev *led_cdev,
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enum led_brightness value)
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{
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led_cdev->brightness = min(value, led_cdev->max_brightness);
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if (led_cdev->flags & LED_SUSPENDED)
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return;
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led_set_brightness_nopm(led_cdev, led_cdev->brightness);
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}
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EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
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int led_set_brightness_sync(struct led_classdev *led_cdev,
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enum led_brightness value)
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{
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if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
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return -EBUSY;
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led_cdev->brightness = min(value, led_cdev->max_brightness);
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if (led_cdev->flags & LED_SUSPENDED)
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return 0;
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return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
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}
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EXPORT_SYMBOL_GPL(led_set_brightness_sync);
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int led_update_brightness(struct led_classdev *led_cdev)
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{
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int ret = 0;
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if (led_cdev->brightness_get) {
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ret = led_cdev->brightness_get(led_cdev);
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if (ret >= 0) {
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led_cdev->brightness = ret;
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return 0;
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}
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(led_update_brightness);
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/* Caller must ensure led_cdev->led_access held */
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void led_sysfs_disable(struct led_classdev *led_cdev)
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{
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lockdep_assert_held(&led_cdev->led_access);
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led_cdev->flags |= LED_SYSFS_DISABLE;
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}
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EXPORT_SYMBOL_GPL(led_sysfs_disable);
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/* Caller must ensure led_cdev->led_access held */
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void led_sysfs_enable(struct led_classdev *led_cdev)
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{
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lockdep_assert_held(&led_cdev->led_access);
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led_cdev->flags &= ~LED_SYSFS_DISABLE;
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}
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EXPORT_SYMBOL_GPL(led_sysfs_enable);
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