Messages in this thread | | | Subject | Re: [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018 RGB driver | From | Jacek Anaszewski <> | Date | Wed, 9 Jan 2019 22:28:18 +0100 |
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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 <dmurphy@ti.com> >>>>>>> --- >>>>>>> .../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.
common LED bindings say:
- led-sources : List of device current outputs the LED is connected to. The outputs are identified by the numbers that must be defined in the LED device binding documentation.
>> We could additionally mark banks with ti,control-bank, > > We would have to keep the ti,control-bank node based on the above. > >> 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? >> > > No it does not. LED_CONFIG0 sets the bit if it is control bank or not.
OK, so validation will also have to check if led-sources definitions are not mutually exclusive between child DT nodes. For consistency it would be really better if bank definitions also used led-sources.
> Section 8.3.2 in the data sheet says > "When a channel is configured in > LED bank-control mode, the related color mixing and intensity control is governed by the bank control registers > (BANK_A_COLOR, BANK_B_COLOR, BANK_C_COLOR, and BANK_BRIGHTNESS) regardless of the inputs > on its own color-mixing and intensity-control registers." >
-- Best regards, Jacek Anaszewski
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