linux-kernel - Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event

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Message-ID: <57042FD8.1090100@gmail.com>
Date:	Tue, 5 Apr 2016 23:36:24 +0200
From:	Jacek Anaszewski <jacek.anaszewski@...il.com>
To:	Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
	linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc:	Richard Purdie <rpurdie@...ys.net>,
	Jacek Anaszewski <j.anaszewski@...sung.com>
Subject: Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API

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@...guardiasur.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.

> +	list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
> +		if (nosleep)
> +			led_set_brightness_nosleep(led_cdev, brightness);
> +		else
> +			led_set_brightness(led_cdev, brightness);
> +	}
>   	read_unlock(&trig->leddev_list_lock);
>   }
> +
> +void led_trigger_event(struct led_trigger *trig,
> +		       enum led_brightness brightness)
> +{
> +	do_led_trigger_event(trig, brightness, false);
> +}
>   EXPORT_SYMBOL_GPL(led_trigger_event);
>
> +void led_trigger_event_nosleep(struct led_trigger *trig,
> +			       enum led_brightness brightness)
> +{
> +	do_led_trigger_event(trig, brightness, true);
> +}
> +EXPORT_SYMBOL_GPL(led_trigger_event_nosleep);
> +
>   static void led_trigger_blink_setup(struct led_trigger *trig,
>   			     unsigned long *delay_on,
>   			     unsigned long *delay_off,
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 7f1428bb1e69..d33b230ce66d 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -259,6 +259,8 @@ extern void led_trigger_register_simple(const char *name,
>   extern void led_trigger_unregister_simple(struct led_trigger *trigger);
>   extern void led_trigger_event(struct led_trigger *trigger,
>   				enum led_brightness event);
> +extern void led_trigger_event_nosleep(struct led_trigger *trigger,
> +				enum led_brightness event);
>   extern void led_trigger_blink(struct led_trigger *trigger,
>   			      unsigned long *delay_on,
>   			      unsigned long *delay_off);
> @@ -305,6 +307,8 @@ static inline void led_trigger_register_simple(const char *name,
>   static inline void led_trigger_unregister_simple(struct led_trigger *trigger) {}
>   static inline void led_trigger_event(struct led_trigger *trigger,
>   				enum led_brightness event) {}
> +static inline void led_trigger_event_nosleep(struct led_trigger *trigger,
> +				enum led_brightness event) {}
>   static inline void led_trigger_blink(struct led_trigger *trigger,
>   				      unsigned long *delay_on,
>   				      unsigned long *delay_off) {}
>

-- 
Best regards,
Jacek Anaszewski