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[83.24.98.218]) by smtp.gmail.com with ESMTPSA id z6sm12620947lfa.87.2019.01.07.13.14.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Jan 2019 13:14:01 -0800 (PST) Subject: Re: [PATCH 2/2] leds: lp5024: Add the LP5024/18 RGB LED driver To: =?UTF-8?B?VmVzYSBKw6TDpHNrZWzDpGluZW4=?= , 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> <90a2ed79-b437-af14-4538-430d8723cc6b@gmail.com> From: Jacek Anaszewski Message-ID: <38daf022-e4e4-799d-4c75-ee851315290d@gmail.com> Date: Mon, 7 Jan 2019 22:13:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <90a2ed79-b437-af14-4538-430d8723cc6b@gmail.com> 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 Vesa, On 1/5/19 1:39 AM, Vesa Jääskeläinen wrote: > 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? I'd prefer to have single RGB LED device. And your DT design is unnecessarily complex and a bit confusing. Also, you provided scarce information about sysfs interface. It would be nice to see the sequence of commands. -- Best regards, Jacek Anaszewski