linux-kernel - Re: [PATCH 4/4] leds: trigger: Add pattern initialization from Device Tree

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Date:   Sun, 9 Dec 2018 19:55:26 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>, Pavel Machek <pavel@....cz>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Baolin Wang <baolin.wang@...aro.org>,
        Raphael Teysseyre <rteysseyre@...il.com>,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] leds: trigger: Add pattern initialization from Device
 Tree

On 12/8/18 7:44 PM, Jacek Anaszewski wrote:
> Hi Krzysztof,
> 
> Thank you for the patch set.
> 
> Applied 1/4 and 2/4.
> 
> I'll hold on merging 3/4 until we sort out the issues
> I have with this one. Please refer to my comment below.
> 
> On 12/7/18 1:32 PM, Krzysztof Kozlowski wrote:
>> Allow initialization of pattern used in pattern trigger from Device Tree
>> property.
>>
>> This is especially useful for embedded systems where the pattern trigger
>> would be used to indicate the process of boot status in a nice,
>> user-friendly blinking way.  This initialization pattern will be used
>> till user-space is brought up and sets its own pattern, indicating the
>> boot status is for example finished.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
>> ---
>>   drivers/leds/trigger/ledtrig-pattern.c | 18 ++++++++++++++++++
>>   1 file changed, 18 insertions(+)
>>
>> diff --git a/drivers/leds/trigger/ledtrig-pattern.c 
>> b/drivers/leds/trigger/ledtrig-pattern.c
>> index 1870cf87afe1..96309d3bc43c 100644
>> --- a/drivers/leds/trigger/ledtrig-pattern.c
>> +++ b/drivers/leds/trigger/ledtrig-pattern.c
>> @@ -11,6 +11,7 @@
>>   #include <linux/leds.h>
>>   #include <linux/module.h>
>>   #include <linux/mutex.h>
>> +#include <linux/of.h>
>>   #include <linux/slab.h>
>>   #include <linux/timer.h>
>> @@ -331,6 +332,21 @@ static const struct attribute_group 
>> *pattern_trig_groups[] = {
>>       NULL,
>>   };
>> +static void pattern_init(struct led_classdev *led_cdev)
>> +{
>> +    struct device_node *np = dev_of_node(led_cdev->dev);
>> +    const char *pattern;
>> +
>> +    if (!np)
>> +        return;
>> +
>> +    if (!of_property_read_string(np, "linux,trigger-pattern", 
>> &pattern)) {
>> +        if (strlen(pattern))
>> +            pattern_trig_store_patterns(led_cdev, pattern,
>> +                            strlen(pattern), false);
>> +    }
>> +}
>> +
>>   static int pattern_trig_activate(struct led_classdev *led_cdev)
>>   {
>>       struct pattern_trig_data *data;
>> @@ -354,6 +370,8 @@ static int pattern_trig_activate(struct 
>> led_classdev *led_cdev)
>>       timer_setup(&data->timer, pattern_trig_timer_function, 0);
>>       led_cdev->activated = true;
>> +    pattern_init(led_cdev);

With my recent patches it would suffice to replace above line with:

if (led_cdev->flags & LED_INIT_DEFAULT_TRIGGER) {
	pattern_init(led_cdev);
	led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
}

> It means that the pattern defined in DT would be applied
> whenever the pattern trigger is set for a LED class device,
> whereas it should happen only on LED class device initialization,
> if linux,default-trigger is set to "pattern".
> 
> What we would need for making that work is a generic support for
> parsing trigger specific initialization data in the
> of_led_classdev_register().
> 
>> +
>>       return 0;
>>   }
>>
> 

-- 
Best regards,
Jacek Anaszewski