From 7cfe749fad5158247282f2fee30773fd454029ab Mon Sep 17 00:00:00 2001 From: Tony Makkiel Date: Wed, 18 May 2016 17:22:45 +0100 Subject: leds: core: Fix brightness setting upon hardware blinking enabled Commit 76931edd54f8 ("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: f1e80c07416a ("leds: core: Add two new LED_BLINK_ flags") Signed-off-by: Tony Makkiel Signed-off-by: Jacek Anaszewski --- Documentation/leds/leds-class.txt | 4 ++-- drivers/leds/led-core.c | 9 ++++++--- include/linux/leds.h | 23 ++++++++++++----------- 3 files changed, 20 insertions(+), 16 deletions(-) diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt index d406d98339b2..44f5e6bccd97 100644 --- a/Documentation/leds/leds-class.txt +++ b/Documentation/leds/leds-class.txt @@ -74,8 +74,8 @@ blink_set() function (see ). To set an LED to blinking, however, it is better to use the API function led_blink_set(), as it will check and implement software fallback if necessary. -To turn off blinking again, use the API function led_brightness_set() -as that will not just set the LED brightness but also stop any software +To turn off blinking, use the API function led_brightness_set() +with brightness value LED_OFF, which should stop any software timers that may have been required for blinking. The blink_set() function should choose a user friendly blinking value diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index 3495d5d6547f..3bce44893021 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -53,11 +53,12 @@ static void led_timer_function(unsigned long data) if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) { led_set_brightness_nosleep(led_cdev, LED_OFF); + led_cdev->flags &= ~LED_BLINK_SW; return; } if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) { - led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP; + led_cdev->flags &= ~(LED_BLINK_ONESHOT_STOP | LED_BLINK_SW); return; } @@ -151,6 +152,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev, return; } + led_cdev->flags |= LED_BLINK_SW; mod_timer(&led_cdev->blink_timer, jiffies + 1); } @@ -219,6 +221,7 @@ void led_stop_software_blink(struct led_classdev *led_cdev) del_timer_sync(&led_cdev->blink_timer); led_cdev->blink_delay_on = 0; led_cdev->blink_delay_off = 0; + led_cdev->flags &= ~LED_BLINK_SW; } EXPORT_SYMBOL_GPL(led_stop_software_blink); @@ -226,10 +229,10 @@ void led_set_brightness(struct led_classdev *led_cdev, enum led_brightness brightness) { /* - * In case blinking is on delay brightness setting + * If software blink is active, delay brightness setting * until the next timer tick. */ - if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) { + if (led_cdev->flags & LED_BLINK_SW) { /* * If we need to disable soft blinking delegate this to the * work queue task to avoid problems in case we are called diff --git a/include/linux/leds.h b/include/linux/leds.h index d2b13066e781..e5e7f2e80a54 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -42,15 +42,16 @@ struct led_classdev { #define LED_UNREGISTERING (1 << 1) /* Upper 16 bits reflect control information */ #define LED_CORE_SUSPENDRESUME (1 << 16) -#define LED_BLINK_ONESHOT (1 << 17) -#define LED_BLINK_ONESHOT_STOP (1 << 18) -#define LED_BLINK_INVERT (1 << 19) -#define LED_BLINK_BRIGHTNESS_CHANGE (1 << 20) -#define LED_BLINK_DISABLE (1 << 21) -#define LED_SYSFS_DISABLE (1 << 22) -#define LED_DEV_CAP_FLASH (1 << 23) -#define LED_HW_PLUGGABLE (1 << 24) -#define LED_PANIC_INDICATOR (1 << 25) +#define LED_BLINK_SW (1 << 17) +#define LED_BLINK_ONESHOT (1 << 18) +#define LED_BLINK_ONESHOT_STOP (1 << 19) +#define LED_BLINK_INVERT (1 << 20) +#define LED_BLINK_BRIGHTNESS_CHANGE (1 << 21) +#define LED_BLINK_DISABLE (1 << 22) +#define LED_SYSFS_DISABLE (1 << 23) +#define LED_DEV_CAP_FLASH (1 << 24) +#define LED_HW_PLUGGABLE (1 << 25) +#define LED_PANIC_INDICATOR (1 << 26) /* Set LED brightness level * Must not sleep. Use brightness_set_blocking for drivers @@ -72,8 +73,8 @@ struct led_classdev { * and if both are zero then a sensible default should be chosen. * The call should adjust the timings in that case and if it can't * match the values specified exactly. - * Deactivate blinking again when the brightness is set to a fixed - * value via the brightness_set() callback. + * Deactivate blinking again when the brightness is set to LED_OFF + * via the brightness_set() callback. */ int (*blink_set)(struct led_classdev *led_cdev, unsigned long *delay_on, -- cgit v1.2.3