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[88.156.142.67]) by smtp.gmail.com with ESMTPSA id d10-20020a056512368a00b0049e9122bd0esm166301lfs.114.2022.11.30.00.33.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Nov 2022 00:33:09 -0800 (PST) Message-ID: <08bd485b-51f6-8249-63a7-a6864a431276@linaro.org> Date: Wed, 30 Nov 2022 09:33:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH 2/3] dt-bindings: leds: add dt schema for worldsemi,ws2812b-spi Content-Language: en-US To: Sebastian Reichel Cc: Chuanhong Guo , linux-leds@vger.kernel.org, Pavel Machek , Rob Herring , Krzysztof Kozlowski , Stanislav Jakubek , Linus Walleij , Shawn Guo , Johan Hovold , Bjorn Andersson , Marijn Suijten , Sven Schwermer , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , open list References: <20221129140955.137361-1-gch981213@gmail.com> <20221129140955.137361-3-gch981213@gmail.com> <98b72494-3188-76d5-2e24-9dc127a8b31a@linaro.org> <20221130001459.3wyxnwpjaxvla6oj@mercury.elektranox.org> From: Krzysztof Kozlowski In-Reply-To: <20221130001459.3wyxnwpjaxvla6oj@mercury.elektranox.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/11/2022 01:14, Sebastian Reichel wrote: >>> + default-intensity: >>> + description: | >>> + An array of 3 integer specifying the default intensity of each color >>> + components in this LED. <255 255 255> if unspecified. >>> + $ref: /schemas/types.yaml#/definitions/uint32-array >>> + minItems: 3 >> >> Drop minItems.... but: >> >>> + maxItems: 3 >>> + items: >>> + minimum: 0 >>> + maximum: 255 >> >> default: 255 > > I would argue, that the default should be 0 (off) instead of 255 > (full power). Yes. > >> What controls the intensity? Don't you have PWM there? > > WS2812 is a RGB led, which contains a small Microcontroller. The µC > takes 24 byte intensity data from a serial input and then passes on > any following bits to the next LED. SPI clk and chip-select are > ignored (chip-select support can be trivially added though). > > You can find them everywhere nowadays, since they are quite cheap > (a few cents per LED) and need only one MOSI pin to control hundreds > of LEDs. OK. This should be anyway existing property, so default-brightness. Best regards, Krzysztof