linux-kernel - Re: [FYI] lm3532: right registration to work with LED-backlight

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Date:   Tue, 17 Sep 2019 19:23:02 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Pavel Machek <pavel@....cz>
Cc:     Tony Lindgren <tony@...mide.com>,
        kernel list <linux-kernel@...r.kernel.org>, sre@...nel.org,
        nekit1000@...il.com, mpartap@....net, merlijn@...zup.org,
        Dan Murphy <dmurphy@...com>, linux-leds@...r.kernel.org
Subject: Re: [FYI] lm3532: right registration to work with LED-backlight

Hi Pavel,

On 9/17/19 2:42 PM, Pavel Machek wrote:
> Hi!
> 
>>>>> +++ b/drivers/leds/leds-lm3532.c
>>>>> @@ -629,7 +629,7 @@ static int lm3532_parse_node(struct lm3532_data *priv)
>>>>>  
>>>>>  		lm3532_init_registers(led);
>>>>>  
>>>>> -		ret = devm_led_classdev_register(priv->dev, &led->led_dev);
>>>>> +		ret = devm_of_led_classdev_register(priv->dev, to_of_node(child), &led->led_dev);
>>>>
>>>> We no longer have devm_of_led_classdev_register(). You must use
>>>> devm_led_classdev_register_ext().
>>>
>>> Something like this (untested)?
> 
>> If you want to properly switch to the new extended LED registration
>> API, then you need:
>>
>> .default_label = ":",
>> .devicename = led->client->name;
>>
>> and in addition to that you need to remove old way of composing
>> the LED name. Something like patch [0] for leds-lm3692x.c.
>> And also patch for DT for consistency would be needed (like [1]).
>>
>> However it will not change anything in LED naming in comparison
>> to the existing code, except that it will enable the possibility
>> of using 'function' and 'color' DT properties instead of deprecated
>> 'label'.
>>
>> I suppose that you expected some extra bonus by passing
>> DT node, but I'm not sure what exactly. Possibly you confused
>> this with the patch set [2] that allows for instantiating
>> backlight device on top of LED class device (it has been forgotten
>> btw and will miss 5.4).
> 
> Yes, it is for LED backlight. Thanks for hints, you have corrected
> version in your inbox.

You need also below cleanups. Please compare my patches reworking
existing drivers in the for-next branch.

diff --git a/drivers/leds/leds-lm3532.c b/drivers/leds/leds-lm3532.c
index 0507c6575c08..fc166f1a1789 100644
--- a/drivers/leds/leds-lm3532.c
+++ b/drivers/leds/leds-lm3532.c
@@ -9,7 +9,6 @@
 #include <linux/types.h>
 #include <linux/regulator/consumer.h>
 #include <linux/module.h>
-#include <uapi/linux/uleds.h>
 #include <linux/gpio/consumer.h>

 #define LM3532_NAME "lm3532-led"
@@ -128,7 +127,6 @@ struct lm3532_als_data {
  * @full_scale_current - The full-scale current setting for the current
sink.
  * @led_strings - The LED strings supported in this array
  * @enabled - Enabled status
- * @label - LED label
  */
 struct lm3532_led {
        struct led_classdev led_dev;
@@ -141,7 +139,6 @@ struct lm3532_led {
        int full_scale_current;
        int enabled:1;
        u32 led_strings[LM3532_MAX_CONTROL_BANKS];
-       char label[LED_MAX_NAME_SIZE];
 };

 /**
@@ -639,16 +636,7 @@ static int lm3532_parse_node(struct lm3532_data *priv)
                fwnode_property_read_string(child, "linux,default-trigger",
                                            &led->led_dev.default_trigger);

-               ret = fwnode_property_read_string(child, "label", &name);
-               if (ret)
-                       snprintf(led->label, sizeof(led->label),
-                               "%s::", priv->client->name);
-               else
-                       snprintf(led->label, sizeof(led->label),
-                                "%s:%s", priv->client->name, name);
-
                led->priv = priv;
-               led->led_dev.name = led->label;
                led->led_dev.brightness_set_blocking =
lm3532_brightness_set;

                ret = devm_led_classdev_register(priv->dev, &led->led_dev);

-- 
Best regards,
Jacek Anaszewski