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[2001:14ba:8017:3300:4da2:4604:cb6f:7dbe]) by smtp.googlemail.com with ESMTPSA id 65sm11590526lfp.55.2019.01.04.16.39.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 04 Jan 2019 16:39:44 -0800 (PST) Subject: Re: [PATCH 2/2] leds: lp5024: Add the LP5024/18 RGB LED driver To: Jacek Anaszewski , Pavel Machek Cc: Dan Murphy , robh+dt@kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org References: <8740cfd6-a6b5-ad27-313b-984a9febf18a@ti.com> <20181219201047.GA23448@amd> <54f28115-0a7d-8e9c-3bec-6e91fb3981ec@gmail.com> <986b5105-2fdb-bd25-7c8a-ca8fd1ade821@gmail.com> <7f205102-e854-f1cb-cc03-1307d1cddc87@gmail.com> <20190104201256.GA2931@amd> From: =?UTF-8?B?VmVzYSBKw6TDpHNrZWzDpGluZW4=?= Message-ID: <90a2ed79-b437-af14-4538-430d8723cc6b@gmail.com> Date: Sat, 5 Jan 2019 02:39:43 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jacek, On 04/01/2019 23.37, Jacek Anaszewski wrote: > But, aside from that hypothetic issue, we need a solution for > LEDn_BRIGHTNESS feature of lp5024, i.e. setting color intensity > via a single register write. How would you propose to address that? You could model it to something like this in device tree: led-module @ { compatible = "lp5024"; // There is in hardware setup to use either linear or // logarithmic scaling: //enable-logarithmic-brightness; led0 { // this will create led instance for LED0 in lp5024 label = "lp-led0"; // This specifies LED number within lp5024 led-index = <0>; // set output-base as 0*3 == 0 element-red { // refers to OUT0 output-offset = <0>; }; element-green { // refers to OUT1 output-offset = <1>; }; element-blue { // refers to OUT2 output-offset = <2>; }; }; led1 { // this will create led instance for LED1 in lp5024 label = "lp-led1"; // This specifies LED number within lp5024 led-index = <1>; // set output-base as 1*3 == 3 element-red { // refers to OUT3 output-offset = <0>; }; element-green { // refers to OUT4 output-offset = <1>; }; element-blue { // refers to OUT5 output-offset = <2>; }; }; bank-led { // this will create led instance for bank leds in lp5024 label = "lp-bank-led"; // configured bank led configuration led-index = <2 3 4 5 6 7>; // As here is list of led-indices this entry is // assumed to be bank configuration. Bank mode is enable // for the indices. // set output-base as BANK A element-red { // refers to BANK A output-offset = <0>; }; element-green { // refers to BANK B output-offset = <1>; }; element-blue { // refers to BANK C output-offset = <2>; }; }; }; This would then create three led instances and each led instance has brightness setting and that goes straight to hardware. If one would want to override hardware control for brightness then I suppose you would define in led node something like: brightness-model = "hsl" This would then pick red, green and blue elements for hsl calculations and others color elements for linear. LED specific hardware brightness would then be either 0 or 0xFF depending if all of LED color elements are zero or not. Would that kind of model work? Thanks, Vesa Jääskeläinen