From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3598C4363D for ; Fri, 25 Sep 2020 10:47:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD64521D91 for ; Fri, 25 Sep 2020 10:47:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727521AbgIYKrn (ORCPT ); Fri, 25 Sep 2020 06:47:43 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:52232 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727201AbgIYKrn (ORCPT ); Fri, 25 Sep 2020 06:47:43 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 88E5F1C0C46; Fri, 25 Sep 2020 12:47:40 +0200 (CEST) Date: Fri, 25 Sep 2020 12:47:39 +0200 From: Pavel Machek To: linux-kernel-mentees@lists.linuxfoundation.org, kernel list , linux-leds@vger.kernel.org Subject: Help wanted in LED subsystem Message-ID: <20200925104739.GA26609@amd> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="+QahgC5+KEYLbs62" Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org --+QahgC5+KEYLbs62 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! In linux-next, I published TODO list for LED subsystem. Is that something linux-kernel-mentees could help with? Best regards, Pavel +++ b/drivers/leds/TODO @@ -0,0 +1,58 @@ +-*- org -*- + +* On/off LEDs should have max_brightness of 1 +* Get rid of enum led_brightness + +It is really an integer, as maximum is configurable. Get rid of it, or +make it into typedef or something. + +* Review atomicity requirements in LED subsystem + +Calls that may and that may not block are mixed in same structure, and +semantics is sometimes non-intuitive. (For example blink callback may +not sleep.) Review the requirements for any bugs and document them +clearly. + +* LED names are still a mess + +No two LEDs have same name, so the names are probably unusable for the +userland. Nudge authors into creating common LED names for common +functionality. + +? Perhaps check for known LED names during boot, and warn if there are +LEDs not on the list? + +* Split drivers into subdirectories + +The number of drivers is getting big, and driver for on/off LED on a +i/o port is really quite different from camera flash LED, which is +really different from driver for RGB color LED that can run its own +microcode. Split the drivers somehow. + +* Figure out what to do with RGB leds + +Multicolor is a bit too abstract. Yes, we can have +Green-Magenta-Ultraviolet LED, but so far all the LEDs we support are +RGB, and not even RGB-White or RGB-Yellow variants emerged. + +Multicolor is not a good fit for RGB LED. It does not really know +about LED color. In particular, there's no way to make LED "white". + +Userspace is interested in knowing "this LED can produce arbitrary +color", which not all multicolor LEDs can. + + Proposal: let's add "rgb" to led_colors in drivers/leds/led-core.c, + add corresponding device tree defines, and use that, instead of + multicolor for RGB LEDs. + + We really need to do that now; "white" stuff can wait. + +RGB LEDs are quite common, and it would be good to be able to turn LED +white and to turn it into any arbitrary color. It is essential that +userspace is able to set arbitrary colors, and it might be good to +have that ability from kernel, too... to allow full-color triggers. + +* Command line utility to manipulate the LEDs? + +/sys interface is not really suitable to use by hand, should we have +an utility to perform LED control? --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --+QahgC5+KEYLbs62 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAl9tyssACgkQMOfwapXb+vJwYwCdG0auv9aF9khVFQIS3OPAAcqk mMkAniskimJAzmhYhVGKqTW4+k7j3T3f =IOvW -----END PGP SIGNATURE----- --+QahgC5+KEYLbs62--