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Subject: Re: [PATCH v3 1/2] leds: core: Introduce LED pattern trigger
To:     Baolin Wang <baolin.wang@linaro.org>, pavel@ucw.cz
Cc:     rteysseyre@gmail.com, bjorn.andersson@linaro.org,
        broonie@kernel.org, linux-leds@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <66b08912a2f9f9f013913162f65abc8f94c066cf.1533400193.git.baolin.wang@linaro.org>
From:   Jacek Anaszewski <jacek.anaszewski@gmail.com>
Message-ID: <8c392d63-15b6-b6fb-f92d-b33ec616883c@gmail.com>
Date:   Sat, 4 Aug 2018 23:41:56 +0200
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Hi Baolin,

Thank you for the new version of the patch set.

On 08/04/2018 06:51 PM, Baolin Wang wrote:
> Some LED controllers have support for autonomously controlling
> brightness over time, according to some preprogrammed pattern or
> function.
> 
> This patch adds pattern trigger that LED device can configure the
> pattern and trigger it.
> 
> Signed-off-by: Raphael Teysseyre <rteysseyre@gmail.com>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
> Changes from v2:
>  - Remove hardware_pattern boolen.
>  - Chnage the pattern string format.
> 
> Changes from v1:
>  - Use ATTRIBUTE_GROUPS() to define attributes.
>  - Introduce hardware_pattern flag to determine if software pattern
>  or hardware pattern.
>  - Re-implement pattern_trig_store_pattern() function.
>  - Remove pattern_get() interface.
>  - Improve comments.
>  - Other small optimization.
> ---
>  .../ABI/testing/sysfs-class-led-trigger-pattern    |  21 ++
>  drivers/leds/trigger/Kconfig                       |   7 +
>  drivers/leds/trigger/Makefile                      |   1 +
>  drivers/leds/trigger/ledtrig-pattern.c             | 270 +++++++++++++++++++++
>  include/linux/leds.h                               |  16 ++
>  5 files changed, 315 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-pattern
>  create mode 100644 drivers/leds/trigger/ledtrig-pattern.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-pattern b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
> new file mode 100644
> index 0000000..40afefe
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
> @@ -0,0 +1,21 @@
> +What:		/sys/class/leds/<led>/pattern
> +Date:		August 2018
> +KernelVersion:	4.19
> +Description:
> +		Specify a pattern for the LED, for LED hardware that support
> +		altering the brightness as a function of time.
> +
> +		The pattern is given by a series of tuples, of brightness and
> +		duration (ms). The LED is expected to traverse the series and
> +		each brightness value for the specified duration. Duration of
> +		0 means brightness should immediately change to new value.
> +
> +		The format of the pattern values should be:
> +		"brightness_1 duration_1 brightness_2 duration_2 brightness_3
> +		duration_3 ...".
> +
> +What:		/sys/class/leds/<led>/repeat
> +Date:		August 2018
> +KernelVersion:	4.19
> +Description:
> +		Specify a pattern repeat number. 0 means repeat indefinitely.
> diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
> index 4018af7..b76fc3c 100644
> --- a/drivers/leds/trigger/Kconfig
> +++ b/drivers/leds/trigger/Kconfig
> @@ -129,4 +129,11 @@ config LEDS_TRIGGER_NETDEV
>  	  This allows LEDs to be controlled by network device activity.
>  	  If unsure, say Y.
>  
> +config LEDS_TRIGGER_PATTERN
> +	tristate "LED Pattern Trigger"
> +	help
> +	  This allows LEDs to be controlled by a software or hardware pattern
> +	  which is a series of tuples, of brightness and duration (ms).
> +	  If unsure, say N
> +
>  endif # LEDS_TRIGGERS
> diff --git a/drivers/leds/trigger/Makefile b/drivers/leds/trigger/Makefile
> index f3cfe19..9bcb64e 100644
> --- a/drivers/leds/trigger/Makefile
> +++ b/drivers/leds/trigger/Makefile
> @@ -13,3 +13,4 @@ obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT)	+= ledtrig-transient.o
>  obj-$(CONFIG_LEDS_TRIGGER_CAMERA)	+= ledtrig-camera.o
>  obj-$(CONFIG_LEDS_TRIGGER_PANIC)	+= ledtrig-panic.o
>  obj-$(CONFIG_LEDS_TRIGGER_NETDEV)	+= ledtrig-netdev.o
> +obj-$(CONFIG_LEDS_TRIGGER_PATTERN)	+= ledtrig-pattern.o
> diff --git a/drivers/leds/trigger/ledtrig-pattern.c b/drivers/leds/trigger/ledtrig-pattern.c
> new file mode 100644
> index 0000000..4e20454
> --- /dev/null
> +++ b/drivers/leds/trigger/ledtrig-pattern.c
> @@ -0,0 +1,270 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * LED pattern trigger
> + *
> + * Idea discussed with Pavel Machek. Raphael Teysseyre implemented
> + * the first version, Baolin Wang simplified and improved the approach.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/timer.h>
> +
> +#define MAX_PATTERNS		1024
> +
> +struct pattern_trig_data {
> +	struct led_classdev *led_cdev;
> +	struct led_pattern patterns[MAX_PATTERNS];
> +	struct led_pattern *curr;
> +	struct led_pattern *next;
> +	struct mutex lock;
> +	u32 npatterns;
> +	u32 repeat;
> +	bool is_indefinite;
> +	struct timer_list timer;
> +};
> +
> +static void pattern_trig_update_patterns(struct pattern_trig_data *data)
> +{
> +	data->curr = data->next;
> +	if (!data->is_indefinite && data->curr == data->patterns)
> +		data->repeat--;
> +
> +	if (data->next == data->patterns + data->npatterns - 1)
> +		data->next = data->patterns;
> +	else
> +		data->next++;
> +}
> +
> +static void pattern_trig_timer_function(struct timer_list *t)
> +{
> +	struct pattern_trig_data *data = from_timer(data, t, timer);
> +
> +	mutex_lock(&data->lock);
> +
> +	if (!data->is_indefinite && !data->repeat) {
> +		mutex_unlock(&data->lock);
> +		return;
> +	}
> +
> +	led_set_brightness(data->led_cdev, data->curr->brightness);
> +	mod_timer(&data->timer, jiffies + msecs_to_jiffies(data->curr->delta_t));
> +	pattern_trig_update_patterns(data);
> +
> +	mutex_unlock(&data->lock);
> +}
> +
> +static int pattern_trig_start_pattern(struct pattern_trig_data *data,
> +				      struct led_classdev *led_cdev)
> +{
> +	if (!data->npatterns)
> +		return 0;
> +
> +	if (led_cdev->pattern_set) {
> +		return led_cdev->pattern_set(led_cdev, data->patterns,
> +					     data->npatterns, data->repeat);
> +	}
> +
> +	data->curr = data->patterns;
> +	data->next = data->patterns + 1;
> +	data->timer.expires = jiffies;
> +	add_timer(&data->timer);
> +
> +	return 0;
> +}
> +
> +static ssize_t pattern_trig_show_repeat(struct device *dev,
> +					struct device_attribute *attr,
> +					char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct pattern_trig_data *data = led_cdev->trigger_data;
> +	u32 repeat;
> +
> +	mutex_lock(&data->lock);
> +
> +	repeat = data->repeat;
> +
> +	mutex_unlock(&data->lock);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%u\n", repeat);
> +}
> +
> +static ssize_t pattern_trig_store_repeat(struct device *dev,
> +					 struct device_attribute *attr,
> +					 const char *buf, size_t count)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct pattern_trig_data *data = led_cdev->trigger_data;
> +	unsigned long res;
> +	int err;
> +
> +	err = kstrtoul(buf, 10, &res);
> +	if (err)
> +		return err;
> +
> +	if (!led_cdev->pattern_set)
> +		del_timer_sync(&data->timer);
> +
> +	mutex_lock(&data->lock);
> +
> +	data->repeat = res;
> +
> +	/* 0 means repeat indefinitely */
> +	if (!data->repeat)
> +		data->is_indefinite = true;
> +	else
> +		data->is_indefinite = false;
> +
> +	err = pattern_trig_start_pattern(data, led_cdev);
> +
> +	mutex_unlock(&data->lock);
> +	return err < 0 ? err : count;
> +}
> +
> +static DEVICE_ATTR(repeat, 0644, pattern_trig_show_repeat,
> +		   pattern_trig_store_repeat);
> +
> +static ssize_t pattern_trig_show_pattern(struct device *dev,
> +					 struct device_attribute *attr,
> +					 char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct pattern_trig_data *data = led_cdev->trigger_data;
> +	ssize_t count = 0;
> +	int i;
> +
> +	mutex_lock(&data->lock);
> +
> +	if (!data->npatterns)
> +		goto out;
> +
> +	for (i = 0; i < data->npatterns; i++) {
> +		count += scnprintf(buf + count, PAGE_SIZE - count,
> +				   "%d %d ",
> +				   data->patterns[i].brightness,
> +				   data->patterns[i].delta_t);
> +	}
> +
> +	buf[count - 1] = '\n';
> +
> +out:
> +	mutex_unlock(&data->lock);
> +	return count;
> +}
> +
> +static ssize_t pattern_trig_store_pattern(struct device *dev,
> +					  struct device_attribute *attr,
> +					  const char *buf, size_t count)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct pattern_trig_data *data = led_cdev->trigger_data;
> +	int ccount, cr, offset = 0, err = 0;
> +
> +	if (!led_cdev->pattern_set)
> +		del_timer_sync(&data->timer);
> +
> +	mutex_lock(&data->lock);
> +
> +	data->npatterns = 0;
> +	while (offset < count - 1 && data->npatterns < MAX_PATTERNS) {
> +		cr = 0;
> +		ccount = sscanf(buf + offset, "%d %d %n",
> +				&data->patterns[data->npatterns].brightness,
> +				&data->patterns[data->npatterns].delta_t, &cr);

Providing non numerical character indeed returns error, but afterwards
reading the pattern shows the sequence up to the moment of parsing
error, whereas it should return only new line character.

Moreover, providing improperly formatted pattern causes strange
behavior, where the last correct pattern is played, ending with
brightness 0, followed by max_brightness.

Please compare my tests with use of uleds tool (tools/leds),
which has max_brightness set to 100.

First list is the uledmon context, which reports timestamps along with
brightness changes, and the second one are operations on such
created 'vvv' LED class device.

~/repos/linux-leds/tools/leds$ sudo ./uledmon  vvv
[2826.191274292] 0
[2858.196038411] 1
[2859.231074491] 2
[2868.588010743] 1
[2869.599084809] 2
[2870.623084418] 3
[2875.620029346] 1
[2876.639073381] 2
[2877.663067682] 3
[2878.687097689] 1
[2879.711090613] 2
[2880.735108176] 3
[2881.759108250] 1
[2882.783080242] 2
[2883.807089762] 3
[2908.564080809] 1
[2909.599076585] 2
[2960.843029216] 1
[2961.887101380] 2
[2962.911079383] 3
[2977.067044920] 1
[2978.079073263] 2
[3016.882015017] 1
[3017.887077037] 2
[3018.911095103] 3
[3019.936081843] 0
[3020.956094064] 100
[3033.650032016] 1
[3034.655079947] 2
[3035.679085288] 3
[3036.704048558] 0
[3037.725068257] 100


$/sys/class/leds/vvv# echo "pattern" > trigger
$/sys/class/leds/vvv# echo "1 1000 2 10f00 3 1000" > pattern

bash: echo: write error: Invalid argument
$/sys/class/leds/vvv# cat pattern
1 1000 2 10
$/sys/class/leds/vvv# echo 1 > repeat
$/sys/class/leds/vvv# echo "1 1000 2 1000 3 1000" > pattern

$/sys/class/leds/vvv# echo 1 > repeat

$/sys/class/leds/vvv# echo 3 > repeat

$/sys/class/leds/vvv# echo "1 1000 2 1000 3 dd1000" > pattern

bash: echo: write error: Invalid argument
$/sys/class/leds/vvv# cat pattern
1 1000 2 1000
$/sys/class/leds/vvv# echo 1 > repeat

$/sys/class/leds/vvv#
$/sys/class/leds/vvv#
$/sys/class/leds/vvv# echo "1 1000 2 1000 3 1000 3" > pattern

bash: echo: write error: Invalid argument
$/sys/class/leds/vvv# cat pattern
1 1000 2 1000 3 1000
$/sys/class/leds/vvv# echo 1 > repeat
$/sys/class/leds/vvv# echo "1 1000 2 1000 3 bb" > pattern

bash: echo: write error: Invalid argument
$/sys/class/leds/vvv# cat pattern
1 1000 2 1000
$/sys/class/leds/vvv# echo 1 > repeat

$/sys/class/leds/vvv# echo "" > pattern
$/sys/class/leds/vvv# echo 1 > repeat

$/sys/class/leds/vvv# echo "1 1000" > pattern

$/sys/class/leds/vvv# echo "1 1000" > pattern

> +		if (ccount != 2) {
> +			err = -EINVAL;
> +			goto out;
> +		}
> +
> +		offset += cr;
> +		data->npatterns++;
> +	}
> +
> +	err = pattern_trig_start_pattern(data, led_cdev);
> +
> +out:
> +	mutex_unlock(&data->lock);
> +	return err < 0 ? err : count;
> +}
> +
> +static DEVICE_ATTR(pattern, 0644, pattern_trig_show_pattern,
> +		   pattern_trig_store_pattern);
> +
> +static struct attribute *pattern_trig_attrs[] = {
> +	&dev_attr_pattern.attr,
> +	&dev_attr_repeat.attr,
> +	NULL
> +};
> +ATTRIBUTE_GROUPS(pattern_trig);
> +
> +static int pattern_trig_activate(struct led_classdev *led_cdev)
> +{
> +	struct pattern_trig_data *data;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	if (!!led_cdev->pattern_set ^ !!led_cdev->pattern_clear) {
> +		dev_warn(led_cdev->dev,
> +			 "Hardware pattern ops validation failed\n");
> +		led_cdev->pattern_set = NULL;
> +		led_cdev->pattern_clear = NULL;
> +	}
> +
> +	data->is_indefinite = true;
> +	mutex_init(&data->lock);
> +	data->led_cdev = led_cdev;
> +	led_set_trigger_data(led_cdev, data);
> +	timer_setup(&data->timer, pattern_trig_timer_function, 0);
> +	led_cdev->activated = true;
> +
> +	return 0;
> +}
> +
> +static void pattern_trig_deactivate(struct led_classdev *led_cdev)
> +{
> +	struct pattern_trig_data *data = led_cdev->trigger_data;
> +
> +	if (!led_cdev->activated)
> +		return;
> +
> +	if (led_cdev->pattern_clear)
> +		led_cdev->pattern_clear(led_cdev);
> +	else
> +		del_timer_sync(&data->timer);
> +
> +	led_set_brightness(led_cdev, LED_OFF);
> +	kfree(data);
> +	led_cdev->activated = false;
> +}
> +
> +static struct led_trigger pattern_led_trigger = {
> +	.name = "pattern",
> +	.activate = pattern_trig_activate,
> +	.deactivate = pattern_trig_deactivate,
> +	.groups = pattern_trig_groups,
> +};
> +
> +static int __init pattern_trig_init(void)
> +{
> +	return led_trigger_register(&pattern_led_trigger);
> +}
> +
> +static void __exit pattern_trig_exit(void)
> +{
> +	led_trigger_unregister(&pattern_led_trigger);
> +}
> +
> +module_init(pattern_trig_init);
> +module_exit(pattern_trig_exit);
> +
> +MODULE_AUTHOR("Raphael Teysseyre <rteysseyre@gmail.com");
> +MODULE_AUTHOR("Baolin Wang <baolin.wang@linaro.org");
> +MODULE_DESCRIPTION("LED Pattern trigger");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 834683d..c54712c 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -22,6 +22,7 @@
>  #include <linux/workqueue.h>
>  
>  struct device;
> +struct led_pattern;
>  /*
>   * LED Core
>   */
> @@ -88,6 +89,11 @@ struct led_classdev {
>  				     unsigned long *delay_on,
>  				     unsigned long *delay_off);
>  
> +	int (*pattern_set)(struct led_classdev *led_cdev,
> +			   struct led_pattern *pattern, int len,
> +			   unsigned repeat);
> +	int (*pattern_clear)(struct led_classdev *led_cdev);
> +
>  	struct device		*dev;
>  	const struct attribute_group	**groups;
>  
> @@ -472,4 +478,14 @@ static inline void led_classdev_notify_brightness_hw_changed(
>  	struct led_classdev *led_cdev, enum led_brightness brightness) { }
>  #endif
>  
> +/**
> + * struct led_pattern - brightness value in a pattern
> + * @delta_t: delay until next entry, in milliseconds
> + * @brightness: brightness at time = 0
> + */
> +struct led_pattern {
> +	int delta_t;
> +	int brightness;
> +};
> +
>  #endif		/* __LINUX_LEDS_H_INCLUDED */
> 

-- 
Best regards,
Jacek Anaszewski