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[PATCH 0/5] Extend the LED panic trigger

Started byEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
First post2016-04-04 22:30 +0200
Last post2016-04-06 08:20 +0200
Articles 6 — 2 participants

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  [PATCH 0/5] Extend the LED panic trigger Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> - 2016-04-04 22:30 +0200
    [PATCH 5/5] leds: gpio: Support the panic-blink firmware property Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> - 2016-04-04 22:30 +0200
    [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> - 2016-04-04 22:30 +0200
      Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2016-04-05 23:40 +0200
        Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> - 2016-04-06 06:40 +0200
          Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2016-04-06 08:20 +0200

#1370867 — [PATCH 0/5] Extend the LED panic trigger

FromEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Date2016-04-04 22:30 +0200
Subject[PATCH 0/5] Extend the LED panic trigger
Message-ID<rkjih-dT-7@gated-at.bofh.it>
As per commit 916fe61995 ("leds: trigger: Introduce a kernel panic LED
trigger"), the kernel now supports a new LED trigger to hook on
the panic blink.

However, the only way of using this is to dedicate a LED device
to this function.

To overcome this limitation, the present series introduces the
capability to switch the LED trigger of certain LED devices upon
a kernel panic (using the panic notifier).

The decision of which LEDs should be switched to the panic trigger
is left to each LED device driver. As an example, a devicetree
boolean property is introduced and used in the leds-gpio driver.

Feedback and other ideas on how to implement this are most welcomed.

Ezequiel Garcia (5):
  leds: triggers: Allow to switch the trigger to "panic" on a kernel
    panic
  leds: triggers: Add a led_trigger_event_nosleep API
  leds: trigger: panic: Use led_trigger_event_nosleep
  devicetree: leds: Introduce "panic-blink" optional property
  leds: gpio: Support the panic-blink firmware property

 Documentation/devicetree/bindings/leds/common.txt |  2 +
 drivers/leds/led-triggers.c                       | 78 +++++++++++++++++++++--
 drivers/leds/leds-gpio.c                          |  4 ++
 drivers/leds/trigger/ledtrig-panic.c              |  2 +-
 include/linux/leds.h                              |  6 ++
 5 files changed, 87 insertions(+), 5 deletions(-)

-- 
2.7.0

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#1370868 — [PATCH 5/5] leds: gpio: Support the panic-blink firmware property

FromEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Date2016-04-04 22:30 +0200
Subject[PATCH 5/5] leds: gpio: Support the panic-blink firmware property
Message-ID<rkjik-dT-37@gated-at.bofh.it>
In reply to#1370867
GPIO LEDs are relatively cheap, and so are ideal to blink on
a kernel panic. This commit adds support for the new "panic-blink"
firmware property, allowing to mark a given LED to blink on
a kernel panic.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
---
 drivers/leds/leds-gpio.c | 4 ++++
 include/linux/leds.h     | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
index 61143f55597e..74e35dcaf874 100644
--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -127,6 +127,8 @@ static int create_gpio_led(const struct gpio_led *template,
 	led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
 	if (!template->retain_state_suspended)
 		led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
+	if (template->panic_blink)
+		led_dat->cdev.flags |= LED_BLINK_AT_PANIC;
 
 	ret = gpiod_direction_output(led_dat->gpiod, state);
 	if (ret < 0)
@@ -200,6 +202,8 @@ static struct gpio_leds_priv *gpio_leds_create(struct platform_device *pdev)
 
 		if (fwnode_property_present(child, "retain-state-suspended"))
 			led.retain_state_suspended = 1;
+		if (fwnode_property_present(child, "panic-blink"))
+			led.panic_blink = 1;
 
 		ret = create_gpio_led(&led, &priv->leds[priv->num_leds],
 				      dev, NULL);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index d33b230ce66d..e8e99cc5f99e 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -363,6 +363,7 @@ struct gpio_led {
 	unsigned 	gpio;
 	unsigned	active_low : 1;
 	unsigned	retain_state_suspended : 1;
+	unsigned	panic_blink : 1;
 	unsigned	default_state : 2;
 	/* default_state should be one of LEDS_GPIO_DEFSTATE_(ON|OFF|KEEP) */
 	struct gpio_desc *gpiod;
-- 
2.7.0

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#1370877 — [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API

FromEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Date2016-04-04 22:30 +0200
Subject[PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API
Message-ID<rkjik-dT-53@gated-at.bofh.it>
In reply to#1370867
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);
+	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) {}
-- 
2.7.0

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#1371976 — Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API

FromJacek Anaszewski <jacek.anaszewski@gmail.com>
Date2016-04-05 23:40 +0200
SubjectRe: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API
Message-ID<rkGRB-1Og-37@gated-at.bofh.it>
In reply to#1370877
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.

> +	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

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#1372178 — Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API

FromEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Date2016-04-06 06:40 +0200
SubjectRe: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API
Message-ID<rkNq1-6TB-3@gated-at.bofh.it>
In reply to#1371976
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.

I'm not strongly convinced by any approach, but this API seemed
slightly cleaner.
-- 
Ezequiel García, VanguardiaSur
www.vanguardiasur.com.ar

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#1372213 — Re: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API

FromJacek Anaszewski <jacek.anaszewski@gmail.com>
Date2016-04-06 08:20 +0200
SubjectRe: [PATCH 2/5] leds: triggers: Add a led_trigger_event_nosleep API
Message-ID<rkOYN-880-3@gated-at.bofh.it>
In reply to#1372178
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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