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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92BD3C38A02 for ; Sat, 29 Oct 2022 18:32:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229562AbiJ2ScQ (ORCPT ); Sat, 29 Oct 2022 14:32:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229549AbiJ2ScP (ORCPT ); Sat, 29 Oct 2022 14:32:15 -0400 Received: from jabberwock.ucw.cz (jabberwock.ucw.cz [46.255.230.98]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EDB536BE7 for ; Sat, 29 Oct 2022 11:32:13 -0700 (PDT) Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id D31D81C0049; Sat, 29 Oct 2022 20:32:11 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ucw.cz; s=gen1; t=1667068331; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=UmFGmbJEviSFcQG9H/9i6TZfSnn/vtzwhwvuO/9rSpU=; b=qiwkcV5MuLuRxgVBWyBp028Lt8rk7Sg3t5rcxgHH4C06FTB8VTr3FlUhkat6DcqJZOKfqK EHbzy6StPqo6ftBrJCJbKNUpj3VZawEDG5pprogAUj+eNotmvvRsvqlOMap7FwNAW3AJOX 6awTJUEVnYLCV+ygKfhmF5YDS/ZZ5jc= Date: Sat, 29 Oct 2022 20:32:11 +0200 From: Pavel Machek To: Andreas Bergmeier Cc: linux-leds@vger.kernel.org Subject: Re: Proposal: Add color_temperature support Message-ID: <20221029183211.GA14351@duo.ucw.cz> References: <20221029165218.GA3337@duo.ucw.cz> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="DocE+STaALJfprDB" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-leds@vger.kernel.org --DocE+STaALJfprDB Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > > > On the device Logitech Litra Glow it is possible to set not only the > > > brightness but also the color temperature (both via usb as well as via > > > hardware). > > > I am currently trying to add support for the device - and expose it > > > via LED - into the kernel. > > > So to support all device capabilities I am proposing to extend LEDs by > > > color temperature: > > > And initial patch for the headers: > > > > Internally, the litra glow is something like RGB LED, right? Can we > > support it as a multicolor LED? > The litra glow has 2 control dimensions - brightness and color temperatur= e. > Both dimensions can be controlled in something of a continuous range > (not sure whether these are strictly linear or not). > Thus mapping to RGB would look like more of a very sparse array. > Also, not sure which exact RGB value you would map a color temperature > to anyway. > So at first glance supporting it as a multicolor LED does not seem a > good match to me. Hmm, and there are likely to be more lights like this, right? OTOH it is not really an indicator LED -- using capslock trigger makes little sense with this one. I guess it makes sense to support this in LED subsystem. I believe it should be only supported for "white" LEDs. I believe first step is defining an userspace API in Documentation. Best regards, Pavel --=20 People of Russia, stop Putin before his war on Ukraine escalates. --DocE+STaALJfprDB Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRPfPO7r0eAhk010v0w5/Bqldv68gUCY11xqwAKCRAw5/Bqldv6 8oX9AJkBcjD6tpE9hpee4FIzkLiiC0i3qACghF+brbjUCu3BBVW0HIXbKURRe6w= =V53v -----END PGP SIGNATURE----- --DocE+STaALJfprDB--