Messages in this thread | | | Subject | Re: [PATCH] leds: use led_brightness_set in led_trigger_event | From | Shuah Khan <> | Date | Mon, 11 Jun 2012 15:38:25 -0600 |
| |
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 <fabio.baltieri@gmail.com> > Cc: Bryan Wu <bryan.wu@canonical.com> > --- > 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 along.
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); > }
| |