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

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Date:   Sat, 8 Dec 2018 19:44:35 +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

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);

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