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[83.31.0.231]) by smtp.gmail.com with ESMTPSA id z7sm56752780wrw.22.2019.01.09.12.12.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 Jan 2019 12:12:18 -0800 (PST) Subject: Re: [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018 RGB driver To: Dan Murphy , robh+dt@kernel.org, pavel@ucw.cz Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org References: <20181219162626.12297-1-dmurphy@ti.com> <20181219162626.12297-2-dmurphy@ti.com> <2d2d5dcd-9c23-e901-daac-9b79aa5a5e82@ti.com> <6c62956e-7789-58ba-5437-f2e033f2825c@gmail.com> <366cbf6d-94fa-fea9-be58-07ddb09cff3a@ti.com> From: Jacek Anaszewski Message-ID: Date: Wed, 9 Jan 2019 21:12:15 +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: <366cbf6d-94fa-fea9-be58-07ddb09cff3a@ti.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 Dan, On 1/8/19 10:22 PM, Dan Murphy wrote: > On 1/8/19 3:16 PM, Jacek Anaszewski wrote: >> On 1/8/19 9:53 PM, Dan Murphy wrote: >>> Jacek >>> >>> On 1/8/19 2:33 PM, Jacek Anaszewski wrote: >>>> Dan, >>>> >>>> On 12/19/18 5:26 PM, Dan Murphy wrote: >>>>> Introduce the bindings for the Texas Instruments LP5024 and the LP5018 >>>>> RGB LED device driver.  The LP5024/18 can control RGB LEDs individually >>>>> or as part of a control bank group.  These devices have the ability >>>>> to adjust the mixing control for the RGB LEDs to obtain different colors >>>>> independent of the overall brightness of the LED grouping. >>>>> >>>>> Datasheet: >>>>> http://www.ti.com/lit/ds/symlink/lp5024.pdf >>>>> >>>>> Signed-off-by: Dan Murphy >>>>> --- >>>>>    .../devicetree/bindings/leds/leds-lp5024.txt  | 63 +++++++++++++++++++ >>>>>    1 file changed, 63 insertions(+) >>>>>    create mode 100644 Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/leds/leds-lp5024.txt b/Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>> new file mode 100644 >>>>> index 000000000000..9567aa6f7813 >>>>> --- /dev/null >>>>> +++ b/Documentation/devicetree/bindings/leds/leds-lp5024.txt >>>>> @@ -0,0 +1,63 @@ >>>>> +* Texas Instruments - LP5024/18 RGB LED driver >>>>> + >>>>> +The LM3692x is an ultra-compact, highly efficient, >>>>> +white-LED driver designed for LCD display backlighting. >>>>> + >>>>> +The main difference between the LP5024 and L5018 is the number of >>>>> +RGB LEDs they support.  The LP5024 supports twenty four strings while the >>>>> +LP5018 supports eighteen strings. >>>>> + >>>>> +Required properties: >>>>> +    - compatible: >>>>> +        "ti,lp5018" >>>>> +        "ti,lp5024" >>>>> +    - reg :  I2C slave address >>>>> +    - #address-cells : 1 >>>>> +    - #size-cells : 0 >>>>> + >>>>> +Optional properties: >>>>> +    - enable-gpios : gpio pin to enable/disable the device. >>>>> +    - vled-supply : LED supply >>>>> + >>>>> +Required child properties: >>>>> +    - reg : Is the child node iteration. >>>>> +    - led-sources : LP5024 - 0 - 7 >>>>> +            LP5018 - 0 - 5 >>>>> +            Declares the LED string or strings that the child node >>>>> +            will control.  If ti,control-bank is set then this >>>>> +            property will contain multiple LED IDs. >>>>> + >>>>> +Optional child properties: >>>>> +    - label : see Documentation/devicetree/bindings/leds/common.txt >>>>> +    - linux,default-trigger : >>>>> +       see Documentation/devicetree/bindings/leds/common.txt >>>>> +    - ti,control-bank : Indicates that the LED strings declared in the >>>>> +                led-sources property are grouped within a control >>>>> +                bank for brightness and mixing control. >>>>> + >>>>> +Example: >>>>> + >>>>> +led-controller@28 { >>>>> +    compatible = "ti,lp5024"; >>>>> +    reg = <0x28>; >>>>> +    #address-cells = <1>; >>>>> +    #size-cells = <0>; >>>>> + >>>>> +    enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>; >>>>> +    vled-supply = <&vbatt>; >>>>> + >>>>> +    led@0 { >>>>> +        reg = <0>; >>>>> +        led-sources = <1>; >>>>> +    }; >>>>> + >>>>> +    led@1 { >>>>> +        reg = <1>; >>>>> +        led-sources = <0 6>; >>>>> +        ti,control-bank; >>>> >>>> Do you really need ti,control-bank? Doesn't led-sources array size >>>> greater than 1 mean that the node describes control bank? >>>> >>> >>> That will work too. >> >>>> Also, does it make sense to have only two LEDs in the bank? >>> >>> The array can populate all 7 LEDs in a single node.  I only show 2 here as the example. >>> See the description above of the led-sources >> >> OK, I confused RGB LED modules with banks. >> >> Shouldn't we allow for defining either strings or RGB LED >> triplets somehow then? >> > > Well that is what this should be doing. If you define a single LED in LED sources then > the triplet is controlled via the associated LEDx_brightness register. led-sources should map to iouts directly. So, for RGB LED modules I would expect: LED0: led-sources = <0 1 2>; LED1: led-sources = <3 4 5>; LED2: led-sources = <6 7 8>; and so on. for banks: Bank A with iouts 0,3,6,9: led-sources<0 3 6 9>; Bank B with iouts 2,4,10: led-sources<2 4 10>; Bank C with iouts 5,8,11,14,17: led-sources<5 8 11 14 17>; We could additionally mark banks with ti,control-bank, but I'm not sure if it would ease parsing, since you will have to validate iouts configuration anyway. > If you have multiple LED sources defined in the led-sources then those LEDs would be grouped in the bank. > I guess I need to provide some protection or a warning if a DT defines two banks because there is only one bank control. Does the hardware allow the IOUT to belong to an RGB LED module and to a bank in the same time? -- Best regards, Jacek Anaszewski