Re: [PATCH v3] ARM: dts: renesas: r9a06g032-rzn1d400-db: describe Debug LEDs

[Jacek Anaszewski <jacek.anaszewski@gmail.com>]

Hi all,

On 5/8/25 15:49, Lee Jones wrote:
> On Thu, 08 May 2025, Wolfram Sang wrote:
> 
>> On Thu, Apr 17, 2025 at 01:39:14PM +0200, Geert Uytterhoeven wrote:
>>> Hi Wolfram,
>>>
>>> CC leds
>>>
>>> On Thu, 17 Apr 2025 at 11:33, Wolfram Sang
>>> <wsa+renesas@sang-engineering.com> wrote:
>>>> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
>>>> ---
>>>>
>>>> Changes since v2:
>>>> * using function, color, function-enumerator properties now
>>>>
>>>> Honestly, this is better than using node names? With V2, the LEDs were
>>>> named as in the schematics, now they are called:
>>>>
>>>> lrwxrwxrwx    1 root     root             0 May 12 12:10 green:programming-0 -> ../../devices/platform/leds/leds/green:programming-0
>>>> lrwxrwxrwx    1 root     root             0 May 12 12:10 green:programming-1 -> ../../devices/platform/leds/leds/green:programming-1
>>>> lrwxrwxrwx    1 root     root             0 May 12 12:10 green:programming-2 -> ../../devices/platform/leds/leds/green:programming-2
>>>> ...
>>>>
>>>> Which gets even more confusing if we might later add LEDs not on this
>>>> board, but on the expansion board. 'green:programming-8' sits where?
>>>>
>>>> I really wonder, but if this is the official way now...
>>>
>>> Good point!  So I'm inclined to take v2...
>>>
>>> Let's raise this with the LED people. I don't want to fight Pavel when
>>> v2 hits the CiP tree ;-)
>>
>> So, if there is no other opinion here, can we remove function, color,
>> function-enumerator and just use the node names which match the
>> schematics? Basically apply V2?
> 
> I didn't author the semantics nor the rules surrounding them, but I am
> obliged to enforce them.  Therefore "LED people" say, please stick to
> convention as stated in the present documentation:
> 
> https://docs.kernel.org/leds/leds-class.html#led-device-naming
> 
> Please note that a "debug" (LED_FUNCTION_DEBUG) option already exists if
> that is more appropriate to your use-case.
> 
> Let's also bring Jacek into the conversion, since I know that he did a
> bunch of work around this topic.

The question is if the LED name from the schematics tells anything to
the user of the equipment?

The idea behind LED naming is to facilitate matching the LED class
device name as reported by the system with the LED location on the
equipment.

The LED naming standardization intended to enforce consistent
LED naming, and not allowing to add multiple interchangeable
names like wifi/wlan. It also helps to keep LED name sections order in
accordance with Linux documentation, which before had been often
abused by allowing to assign anything to the now deprecated 'label'
DT property.

Regarding expansion boards - we never have control over what
LED names DT overlays will define, thus LED core adds numeric suffix to
the LED class device name in case of the name clash.

-- 
Best regards,
Jacek Anaszewski