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    SubjectRe: [PATCH] leds: use led_brightness_set in led_trigger_event
    On Mon, 2012-06-11 at 22:57 +0200, Fabio Baltieri wrote:
    > Fix led_trigger_event() to use led_brightness_set() instead of
    > led_set_brightness(), so that any pending blink timer is stopped before
    > setting the new brightness value. Without this fix LED status may be
    > overridden by a pending timer.
    > This allows a trigger to use a mix of led_trigger_event(),
    > led_trigger_blink() and led_trigger_blink_oneshot() without races.
    > Signed-off-by: Fabio Baltieri <>
    > Cc: Bryan Wu <>
    > ---
    > Hi Bryan,
    > I found this one while working on another patch but I think it's also needed by
    > other drivers which mixes led_trigger_blink() and led_trigger_event(), such as
    > power_supply_leds.
    > Without this a led don't stop blinking as it should when calling
    > led_trigger_event().

    Good find. This is very subtle race though because both timer and
    oneshot triggers call led_brightness_set() from their deactivate
    routines. Is this when these events triggered using oneshot trigger?

    > Should not cause any harm on other drivers.
    > (I'm starting to find the whole led_set_brightness/led_brightness_set thing a
    > bit confusing BTW...)

    I agree with the names are confusing. :) It found it confusing as well.
    Probably why we have this bug hiding until led_trigger_blink() came

    led_brightness_set() calls led_set_brightness(). led_set_brightness()
    takes cares about whether the driver is in suspend state and invokes
    driver's brightness_set interface. Maybe led_clear_blink_timer() would
    be a better name for this led_brightness_set() routine.

    I can volunteer to make this change if we agree that this will be a good
    one to clear this naming confusion.

    -- Shuah

    > Fabio
    > drivers/leds/led-triggers.c | 2 +-
    > 1 file changed, 1 insertion(+), 1 deletion(-)
    > diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
    > index fa0b9be..b88d3b9 100644
    > --- a/drivers/leds/led-triggers.c
    > +++ b/drivers/leds/led-triggers.c
    > @@ -224,7 +224,7 @@ void led_trigger_event(struct led_trigger *trig,
    > struct led_classdev *led_cdev;
    > led_cdev = list_entry(entry, struct led_classdev, trig_list);
    > - led_set_brightness(led_cdev, brightness);
    > + led_brightness_set(led_cdev, brightness);

    This is in-line with led_trigger_set() which is calling
    led_bightness_set() correctly. Also led_classdev_unregister() calls it I
    think for the same reason so the blink timer can be stopped.

    > }
    > read_unlock(&trig->leddev_list_lock);
    > }

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