linux-kernel - Re: [PATCH v8 2/5] leds: Add of_led_get() and led_put()

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Message-ID: <acd11fe1-1d51-eda5-f807-c16319514c3a@ti.com>
Date:   Thu, 3 Oct 2019 14:47:11 +0200
From:   Jean-Jacques Hiblot <jjhiblot@...com>
To:     Sebastian Reichel <sebastian.reichel@...labora.com>
CC:     <jacek.anaszewski@...il.com>, <pavel@....cz>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <lee.jones@...aro.org>,
        <daniel.thompson@...aro.org>, <linux-kernel@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <tomi.valkeinen@...com>,
        <dmurphy@...com>, <linux-leds@...r.kernel.org>
Subject: Re: [PATCH v8 2/5] leds: Add of_led_get() and led_put()

Hi Sebastian,

On 03/10/2019 12:42, Sebastian Reichel wrote:
> Hi,
>
> On Thu, Oct 03, 2019 at 10:28:09AM +0200, Jean-Jacques Hiblot wrote:
>> From: Tomi Valkeinen <tomi.valkeinen@...com>
>>
>> This patch adds basic support for a kernel driver to get a LED device.
>> This will be used by the led-backlight driver.
>>
>> Only OF version is implemented for now, and the behavior is similar to
>> PWM's of_pwm_get() and pwm_put().
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...com>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...com>
>> Acked-by: Pavel Machek <pavel@....cz>
>> ---
>>   drivers/leds/led-class.c | 44 ++++++++++++++++++++++++++++++++++++++++
>>   include/linux/leds.h     |  4 ++++
>>   2 files changed, 48 insertions(+)
>>
>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>> index c2167b66b61f..455545f5d663 100644
>> --- a/drivers/leds/led-class.c
>> +++ b/drivers/leds/led-class.c
>> @@ -19,6 +19,7 @@
>>   #include <linux/spinlock.h>
>>   #include <linux/timer.h>
>>   #include <uapi/linux/uleds.h>
>> +#include <linux/of.h>
>>   #include "leds.h"
>>   
>>   static struct class *leds_class;
>> @@ -214,6 +215,49 @@ static int led_resume(struct device *dev)
>>   
>>   static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
>>   
>> +/**
>> + * of_led_get() - request a LED device via the LED framework
>> + * @np: device node to get the LED device from
>> + * @index: the index of the LED
>> + *
>> + * Returns the LED device parsed from the phandle specified in the "leds"
>> + * property of a device tree node or a negative error-code on failure.
>> + */
>> +struct led_classdev *of_led_get(struct device_node *np, int index)
>> +{
>> +	struct device *led_dev;
>> +	struct led_classdev *led_cdev;
>> +	struct device_node *led_node;
>> +
>> +	led_node = of_parse_phandle(np, "leds", index);
>> +	if (!led_node)
>> +		return ERR_PTR(-ENOENT);
>> +
>> +	led_dev = class_find_device_by_of_node(leds_class, led_node);
> If you convert led_node into a fwnode, you can use
> class_find_device_by_fwnode() instead. That way the
> first patch can just be dropped.

Thanks for the reviews.

The first patch could be dropped  indeed, but it would break something 
else I'm working on: getting regulator support in the LED core.

This has been discussed during the v7 iteration of this series.

JJ

>
> -- Sebastian
>
>> +	of_node_put(led_node);
>> +
>> +	if (!led_dev)
>> +		return ERR_PTR(-EPROBE_DEFER);
>> +
>> +	led_cdev = dev_get_drvdata(led_dev);
>> +
>> +	if (!try_module_get(led_cdev->dev->parent->driver->owner))
>> +		return ERR_PTR(-ENODEV);
>> +
>> +	return led_cdev;
>> +}
>> +EXPORT_SYMBOL_GPL(of_led_get);
>> +
>> +/**
>> + * led_put() - release a LED device
>> + * @led_cdev: LED device
>> + */
>> +void led_put(struct led_classdev *led_cdev)
>> +{
>> +	module_put(led_cdev->dev->parent->driver->owner);
>> +}
>> +EXPORT_SYMBOL_GPL(led_put);
>> +
>>   static int led_classdev_next_name(const char *init_name, char *name,
>>   				  size_t len)
>>   {
>> diff --git a/include/linux/leds.h b/include/linux/leds.h
>> index b8df71193329..6f7371bc7757 100644
>> --- a/include/linux/leds.h
>> +++ b/include/linux/leds.h
>> @@ -20,6 +20,7 @@
>>   
>>   struct device;
>>   struct led_pattern;
>> +struct device_node;
>>   /*
>>    * LED Core
>>    */
>> @@ -196,6 +197,9 @@ extern void devm_led_classdev_unregister(struct device *parent,
>>   extern void led_classdev_suspend(struct led_classdev *led_cdev);
>>   extern void led_classdev_resume(struct led_classdev *led_cdev);
>>   
>> +extern struct led_classdev *of_led_get(struct device_node *np, int index);
>> +extern void led_put(struct led_classdev *led_cdev);
>> +
>>   /**
>>    * led_blink_set - set blinking with software fallback
>>    * @led_cdev: the LED to start blinking
>> -- 
>> 2.17.1
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@...ts.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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