Messages in this thread | | | Subject | Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API | From | Jacek Anaszewski <> | Date | Wed, 6 Apr 2016 08:12:40 +0200 |
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On 04/06/2016 06:38 AM, Ezequiel Garcia wrote: > On 5 April 2016 at 18:36, Jacek Anaszewski <jacek.anaszewski@gmail.com> wrote: >> Hi Ezequiel, >> >> >> On 04/04/2016 10:22 PM, Ezequiel Garcia wrote: >>> >>> Now that we can mark any LED (even those in use by delayed blink >>> triggers) to trigger on a kernel panic, let's introduce a nosleep >>> led_trigger_event API. >>> >>> This API is needed to skip the delayed blink path on >>> led_trigger_event. LEDs that are switched on a kernel panic, >>> might be in use by a delayed blink trigger. >>> >>> This will be used by the panic LED trigger. >>> >>> Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> >>> --- >>> drivers/leds/led-triggers.c | 26 ++++++++++++++++++++++---- >>> include/linux/leds.h | 4 ++++ >>> 2 files changed, 26 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c >>> index f5c9d7c4d181..00b9d8497777 100644 >>> --- a/drivers/leds/led-triggers.c >>> +++ b/drivers/leds/led-triggers.c >>> @@ -307,8 +307,9 @@ EXPORT_SYMBOL_GPL(devm_led_trigger_register); >>> >>> /* Simple LED Tigger Interface */ >>> >>> -void led_trigger_event(struct led_trigger *trig, >>> - enum led_brightness brightness) >>> +static void do_led_trigger_event(struct led_trigger *trig, >>> + enum led_brightness brightness, >>> + bool nosleep) >>> { >>> struct led_classdev *led_cdev; >>> >>> @@ -316,12 +317,29 @@ void led_trigger_event(struct led_trigger *trig, >>> return; >>> >>> read_lock(&trig->leddev_list_lock); >>> - list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) >>> - led_set_brightness(led_cdev, brightness); >> >> >> led_set_brightness() can gently disable blinking if passed 0 in the >> brightness argument. IMHO this patch is not needed then. >> >> > > Yes, but the blinking disable is deferred, and so might never > run (e.g. I'd say it won't run on a non-preemptible kernel). > > I think we need this API, or otherwise some way of circumventing > the deferred path on led_set_brightness. For instance, we > could turn off delay_on and delay_off in the panic atomic notifier.
Yes, I prefer the latter, as it requires less changes.
> I'm not strongly convinced by any approach, but this API seemed > slightly cleaner. >
-- Best regards, Jacek Anaszewski
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