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[83.31.2.161]) by smtp.gmail.com with ESMTPSA id g17sm14423061lfg.78.2019.01.10.10.44.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Jan 2019 10:44:45 -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: <1702dfd6-b08f-c1ff-e46d-1366618bedb0@gmail.com> Date: Thu, 10 Jan 2019 19:44:43 +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: 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 1/9/19 10:31 PM, Dan Murphy wrote: > Jacek > > On 1/9/19 3:28 PM, Jacek Anaszewski wrote: >> On 1/9/19 10:12 PM, Dan Murphy wrote: >>> On 1/9/19 2:12 PM, Jacek Anaszewski wrote: >>>> 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>; >>>> >>> >>> Ok the led-sources would need to be different then this as I don't define the sources for banks. >>> >>> The led-sources for the banks and the individual groups will have different meanings within the same >>> document.  I was attempting to keep the led-sources mapped to the LEDx_brightness registers as opposed to >>> the hardware outputs since the RGB LEDs are controlled and grouped by a single brightness register and if banked then >>> it would be controlled by the bank brightness register. >>> >>> Describing these in the DT seems wrought with potential issues as the data sheet defines what outputs map to what bank and LED >>> registers. >> >> Yes, that's why I mentioned the need for validation of led-sources. >> But they have to be iouts. This property was introduced specifically >> for such purposes. >> > > Yes Pavel also mentioned that as well. > > I will look into validating the sources. But there will be no mapping of the sources to the output that is done > in the hardware. This would just be a data sheet mapping since the outputs are not configurable. Hmm, isn't the mapping defined in the hardware via LED_CONFIG0 register? I have an impression that it defines whether LED belongs to an RGB LED module or to a bank. Basing on that I created my DT example above. -- Best regards, Jacek Anaszewski