Messages in this thread | | | Subject | Re: [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018 RGB driver | From | Jacek Anaszewski <> | Date | Thu, 10 Jan 2019 20:57:50 +0100 |
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Dan,
On 1/10/19 8:22 PM, Dan Murphy wrote: > Jacek > > On 1/10/19 12:44 PM, Jacek Anaszewski wrote: >> 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 <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. >>>> >>> >>> 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. >> > > Yes so if you turn on the bank control for LED0 and LED1 then > out 0, 3 are mapped to BANK A > out 1, 4 are mapped to BANK B
Just noticed that I made a mistake in my example, it should have been:
Bank B with iouts 1,4,10: led-sources<1 4 10>;
> out 2, 5 are mapped to BANK C
Correct.
> All done automatically in the hardware and the LED0_BRIGHTNESS and LED1_BRIGHTNESS registers have no affect on the brightness
That's right.
> If we grouped the LEDs into a bank the led-sources would look more like this > led-sources = < 0 1 2 3 4 5 >;
Why? This would be a mix of three banks. Like you listed above. I'm still interpreting led-sources elements as iout identifiers.
> ti,control-bank; // But this can be omitted as led-sources is greater then 3 > > non-banked case would be > led-sources = < 0 1 2 >;
Agreed here. It would be LED0 RGB LED module. > But the actual OUT numbers don't matter in the bank case unless we do the validation. There would need to be an algorithim > that translates these output to the correct LEDx register and CONFIG0 bits. Basically if OUT0 is mapped to the bank then OUT1 and OUT2 > are inherently mapped to the bank.
To three separate banks, right? OUT0 - bank A, OUT1 - bank B, OUT2 - bank C.
> They cannot be separated so the device theoretically treats the RGB group as a single LED. And > when banked it treats the groups of RGBs that are defined as a single LED. > > This is why it was easier use the LEDx out as the virtual out as we only need to define the group number(s) that are controled by the > LED file presented to the user space.
I suspect there is logical clash here due to interpreting led-sources elements as iouts in one case and LEDn modules in the other case.
-- Best regards, Jacek Anaszewski
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