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=-2.5 required=3.0 tests=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 EA221C5B578 for ; Wed, 3 Jul 2019 22:05:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5EA0218A0 for ; Wed, 3 Jul 2019 22:05:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727304AbfGCWFa (ORCPT ); Wed, 3 Jul 2019 18:05:30 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:38371 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727056AbfGCWFa (ORCPT ); Wed, 3 Jul 2019 18:05:30 -0400 Received: by atrey.karlin.mff.cuni.cz (Postfix, from userid 512) id 35F328060B; Thu, 4 Jul 2019 00:05:16 +0200 (CEST) Date: Thu, 4 Jul 2019 00:05:26 +0200 From: Pavel Machek To: David Laight Cc: 'Linus Walleij' , Jacek Anaszewski , Linux LED Subsystem , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , "linux-kernel@vger.kernel.org" , Rob Herring , Dmitry Torokhov , Guenter Roeck , Dan Murphy , Baolin Wang , Daniel Mack , Oleh Kravchenko , Sakari Ailus , Simon Shields Subject: Various LED complexities was Re: [PATCH v5 05/26] leds: core: Add support for composing LED class device names Message-ID: <20190703220526.GB876@amd> References: <20190609190803.14815-1-jacek.anaszewski@gmail.com> <20190609190803.14815-6-jacek.anaszewski@gmail.com> <643e3b10fe9d45b59ed063ffc6d578ff@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="vGgW1X5XWziG23Ko" Content-Disposition: inline In-Reply-To: <643e3b10fe9d45b59ed063ffc6d578ff@AcuMS.aculab.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --vGgW1X5XWziG23Ko Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri 2019-06-28 13:30:30, David Laight wrote: > From: Linus Walleij > > Sent: 28 June 2019 09:46 > ... > > A problem with LEDs is that it invites bikeshedding because it is too > > relateable. >=20 > Bikeshedding leds :-) >=20 > It also isn't at all clear how to handle bi-colour and tri-colour leds. > ISTR the usual interface lets you set the brightness, but more often > leds are single brightness but multi-colour. > Eg the ethernet 'speed' led which is (usually) off/orange/green. >=20 > Changing the brightness either means changing the current or using PWM. > Both really require more hardware support than changing colours. >=20 > I've done some led driving (for a front panel) from a PLD (small FPGA). > As well as the obvious things I did: > - dim: 1/8th on at 80Hz. > - flash: 1/8th on at 4Hz. > - orange: 50-50 red-green at 80Hz on an RGB led. >=20 > There was also the 'ethernet activity' led which could either be driven > by the hardware, or forced on/off/flash by the driver. > If driven by the hardware, the software could read the current state. >=20 > None of this really fitted the Linux leds interface. Well, we are working on some of those :-). But lets discuss that in separate threads. In particular we are working on triggers and RGB LEDs. bi-color LEDs seem to handled as two separate LEDs. Not much expected to change there. =09 Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --vGgW1X5XWziG23Ko Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAl0dJqYACgkQMOfwapXb+vK3+gCgip2UEFe6NwueZy1C3k5AeG/n otAAnjpPCwHWvYp6ku5OriKI1CkGFCYr =31SK -----END PGP SIGNATURE----- --vGgW1X5XWziG23Ko--