Linux-LEDs Archive on
 help / color / Atom feed
From: "Enrico Weigelt, metux IT consult" <>
To: "Vaittinen, Matti" <>,
	"" <>
Cc: "" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>
Subject: Re: [RFC PATCH 0/5] leds: Add DT node finding and parsing to core
Date: Tue, 19 Nov 2019 20:52:04 +0100
Message-ID: <> (raw)
In-Reply-To: <>

On 18.11.19 11:38, Vaittinen, Matti wrote:


>> a) existing DT's (in the field) become incompatible with newer
>>    kernel versions
> This was my main concern. This of course would not mean that we could
> not take this approach for new LED controller drivers - but that would
> (probably) lead to dual led registration interface 

Maybe just a flag for that ? Perhaps the driver could also specify a
list of node names for the LEDs, so led-core can do the lookup for them.

>> b) existing userlands that rely on speicific LED names become
>>    incomatible with newer kernel versions.
> I didn't even think this far, but yes, I see... LED node name might be
> reflected in user-space LED name. I won't start arguing if this is sane
> or not - this is what we seem to be living with today :)

Especially in embedded world, this can really make sense: applications
just use a defined LED name, no matter which board it's running on.
Convention over configuration.

Personally, I also like to use LED subsystem as frontend for things like
gpio-driven relais, etc, and assign semantically fitting names instead
of "technical" ones,

> I didn't invest too much of time on this yet - but at first glimpse it
> seemed that at least some of the drivers did use reg - property with
> fixed value to do the matching. Those could set the property name to
> 'reg' and value to 'X' and leave the DT node lookup and common property
> parsing to the LED core. If my patch won't get too big objection (and
> if no fatal flaws are found from the idea) - then I might try and find
> the time to do some follow-up patches simplifying existing LED
> drivers...

Sounds good :)


Dringender Hinweis: aufgrund existenzieller Bedrohung durch "Emotet"
sollten Sie *niemals* MS-Office-Dokumente via E-Mail annehmen/öffenen,
selbst wenn diese von vermeintlich vertrauenswürdigen Absendern zu
stammen scheinen. Andernfalls droht Totalschaden.
Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert
werden ! Für eine vertrauliche Kommunikation senden Sie bitte ihren
GPG/PGP-Schlüssel zu.
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering -- +49-151-27565287

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-29 12:46 Matti Vaittinen
2019-10-29 12:46 ` [RFC PATCH 1/5] leds: Add common LED binding parsing support to LED class/core Matti Vaittinen
2019-10-29 12:47 ` [RFC PATCH 2/5] dt-bindings: an30259a: example for using fixed LED node names Matti Vaittinen
2019-11-06  3:42   ` Rob Herring
2019-11-06 11:30     ` SPAM (R/EU IT) // " Vaittinen, Matti
2019-10-29 12:47 ` [RFC PATCH 3/5] leds: an30259a: Offload DT node locating and parsing to core Matti Vaittinen
2019-10-29 12:48 ` [RFC PATCH 4/5] dt-bindings: lm3692x: example for using fixed LED node names Matti Vaittinen
2019-10-29 12:48 ` [RFC PATCH 5/5] leds: lm3692x: Offload DT node locating and parsing to core Matti Vaittinen
2019-11-18  9:21 ` [RFC PATCH 0/5] leds: Add DT node finding " Enrico Weigelt, metux IT consult
2019-11-18 10:38   ` Vaittinen, Matti
2019-11-19 19:52     ` Enrico Weigelt, metux IT consult [this message]
2019-11-20  7:37       ` Vaittinen, Matti

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-LEDs Archive on

Archives are clonable:
	git clone --mirror linux-leds/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-leds linux-leds/ \
	public-inbox-index linux-leds

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone