Re: [PATCH v5 03/26] dt-bindings: leds: Add LED_FUNCTION definitions

From: Jacek Anaszewski <jacek.anaszewski@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>, Pavel Machek <pavel@ucw.cz>
Cc: linux-leds@vger.kernel.org,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Rob Herring <robh@kernel.org>,
	dtor@google.com, Guenter Roeck <linux@roeck-us.net>,
	Dan Murphy <dmurphy@ti.com>, Baolin Wang <baolin.wang@linaro.org>,
	Daniel Mack <daniel@zonque.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Oleh Kravchenko <oleg@kaa.org.ua>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Simon Shields <simon@lineageos.org>
Subject: Re: [PATCH v5 03/26] dt-bindings: leds: Add LED_FUNCTION definitions
Date: Fri, 15 Nov 2019 21:14:41 +0100	[thread overview]
Message-ID: <6e937f6a-e527-ef78-768e-03a04c97d640@gmail.com> (raw)
In-Reply-To: <CAMuHMdXkQCVXdsbS1Tf+7wkafJ4JxhxXeh4R7OWOz5uGs-jL5Q@mail.gmail.com>

Hi Geert,

On 11/15/19 2:01 PM, Geert Uytterhoeven wrote:
> Hi Jacek,
> 
> On Sun, Jun 9, 2019 at 9:09 PM Jacek Anaszewski
> <jacek.anaszewski@gmail.com> wrote:
>> Add initial set of common LED function definitions.
>>
>> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
> 
>> --- a/include/dt-bindings/leds/common.h
>> +++ b/include/dt-bindings/leds/common.h
>> @@ -30,4 +31,45 @@
>>  #define LED_COLOR_ID_IR                7
>>  #define LED_COLOR_ID_MAX       8
>>
>> +/* Standard LED functions */
>> +#define LED_FUNCTION_ACTIVITY "activity"
> 
> What's the appropriate function for "general purpose" or "user" LEDs on
> development boards, where the LEDs don't have fixed functions, unlike
> on real products?
> Perhaps just LED_FUNCTION_INDICATOR?

LED_FUNCTION_INDICATOR was introduced to address current occurrences
of indicator LEDs that are customary for LED flash controllers.
Such LEDs usually indicate that camera sensor is capturing images.
In the v5 of the patch set [0] I proposed also a documentation for
LED functions but there was little interest in it and no broader
discussion took place, so I didn't apply it.

It would be good to include that finally to avoid abusing the LED names
for irrelevant use cases.

> I noticed your very initial submission defined LED_FUNCTION_USER "user".
> I couldn't find an explanation for the rationale behind its removal in later
> revisions, or any discussion asking for that.

I was asked at some point to give rationale for standardizing particular
LED names and couldn't have come up with anything convincing for "user".
This is however an initial set of standard LED names, so we can always
add new ones. If you like please submit a patch adding what you deem
is missing.

[0]
https://lore.kernel.org/linux-leds/20190609190803.14815-27-jacek.anaszewski@gmail.com/

-- 
Best regards,
Jacek Anaszewski