Messages in this thread | | | Subject | Re: [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018 RGB driver | From | Jacek Anaszewski <> | Date | Fri, 11 Jan 2019 22:52:19 +0100 |
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Dan,
On 1/11/19 1:38 PM, Dan Murphy wrote: > Jacek > > Sorry I missed some replies > > On 1/10/19 4:03 PM, Jacek Anaszewski wrote: >> On 1/10/19 9:43 PM, Dan Murphy wrote: >>> Jacek >>> >>> On 1/10/19 1:57 PM, Jacek Anaszewski wrote: >>>> 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. >>>> >>> >>> I am as well but as I tried to explain that if you define OUT0 as bank controlled then OUT1 and OUT2 are also bank controlled >>> within the hardware. We have no control of that. If BIT(0) and BIT(1) are set in the LED_CONFIG0 register then OUT0, 1, 2, 3, 4 and 5 are all bank controlled. >> >> There is naming conflict I noticed just now - LEDn_BANK_EN bits >> in LED_CONFIG0 register enable RGB LED modules, and not BANKs (A,B,C). >> >>> These OUTPUTs will appear as a single RGB LED grouping. >> >> Single? W would rather expect that we get two RGB LED modules, whose >> brightness will be controlled via LED0_BRIGHTNESS and LED1_BRIGHTNESS >> registers respectively. >> >>>>> 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. >>> >>> Yes but there is no BANK output pin just like there is no dedicated LEDn output pin. The banks are grouped internally to the device >>> so again if OUT0 and OUT3 are defined as banked then 1, 2, 4, and 5 are all mapped to the bank. 1 BANK brightness register and 3 bank >>> color adjustment registers. >> >> Here as above, I would expect two separate banks - LED0 and LED1. >> Moreover - not 3 color adjustment registers, but six - one per iout: >> OUT0_COLOR to OUT5_COLOR. >> > > When the LEDs are banked the banked LEDs are controlled by the bank registers not the LEDx registers > so you should only see 3 color adjustments on the banked LEDs. > >>>>> 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. >>>> >>> >>> Yes. When the RGBs are banked you have to think of them as a single RGB LED cluster and not as separate RGB LED clusters. >> >> We have RGB LED modules (enabled with LEDn_Bank_EN bits) and three >> banks (A,B,C), which are enabled by default, am I right? > > No. Independent LED modules are enabled by default. You have to explicitly enable the banks. > >> >> Bank A iouts: 0, 3 ,6, 9, 12, 15 >> Bank B iouts: 1, 4, 7, 10, 13, 16 >> Bank C iouts: 2, 5, 8, 11, 14, 17 >> >> When RGB LED module is enabled (via LEDn_Bank_EN bit), >> the BANK_{A.B,C}_COLOR and BANK_BRIGHTNESS registers >> lose control over related IOUTs in favour of LEDn_BRIGHTNESS and >> related OUTn_COLOR registers. Is it correct? > > No it is the opposite. When the bit is enabled LED banking is enabled and the BANK brightness and color registers over > ride the LEDx color and brightness registers. > > Default is independent control of the RGB via the LEDx color and brightness registers. > >> >>> As you know the brightness is controlled by the single BANK_BRIGHTNESS register. So identifying each output in the led-sources is >>> misleading as the hardware does this all on the chip. This is why I just mapped each output to the Virtual LEDx module. >> >> Ekhm, I messed something here. >> >> So for this I would define a single LED class device. >> Related DT node would not need led-sources at all, >> but only ti,control-bank. The semantics would be: >> controls all iouts not taken by RGB LED modules. >> > > Hmm. I guess I will put that on hold until you read the responses. I am not sure that would work or > that would be really clean. I still believe that mapping led-sources to the LEDx module number is the cleanest > simplest solution since the driver cannot inter mix different outputs for enablement.
I've read the doc again more carefully and hopefully I finally have proper understanding. Let's check it.
1. On reset LED_CONFIG0 bits are zeroed, which means LEDn module independent control mode. 2. LEDn modules (i.e. IOUT triplets) are controlled independently, with use of LEDn_BRIGHTNESS registers, and each IOUT color can be adjusted using OUTn_CONTROL registers. 3. LEDn_Bank_EN bits, when set to 1, assign given RGB LED module to one global bank, controlled via BANK_BRIGHTNESS and BANK_n_COLOR registers.
Having that, I'd see led-sources definitions as follows (led-sources element is IOUT identifier)
1.
- LED0, LED1, LED2, LED3 modules controlled by separate LED class devices
led-sources = <0 1 2> // LED0 led-sources = <3 4 5> // LED1 led-sources = <6 7 8> // LED2 led-sources = <9 10 11> // LED3
2.
- LED0 and LED3 modules assigned to the bank, and controlled by one LED class device, - LED1 and LED2 modules controlled by separate LED class devices
led-sources = <0 1 2 9 10 11> // Bank with LED0 and LED3 led-sources = <3 4 5> // LED1 led-sources = <6 7 8> // LED2
So now I see your point. It would be indeed easier to switch to LEDn module identifiers for led-sources elements. With that the definitions would look like this:
1.
- LED0, LED1, LED2, LED3 modules controlled by separate LED class devices
led-sources = <0> // LED0 led-sources = <1> // LED1 led-sources = <2> // LED2 led-sources = <3> // LED3
2.
- LED0 and LED3 modules assigned to the bank, and controlled by one LED class device, - LED1 and LED2 modules controlled by separate LED class devices
led-sources = <0 3> // Bank with LED0 and LED3 led-sources = <1> // LED1 led-sources = <2> // LED2
But, I don't think use of led-sources is justified in this case. I propose to introduce device specific properties:
ti,led-module and ti,led-bank
With that we would have:
ti,led-bank = <0 3> // Bank with LED0 and LED3 modules ti,led-module = <1> // LED1 ti.led-module = <2> // LED2
>> I would also add Table 1 contents (Bank Number and LED Number >> Assignment) to the DT bindings. >> > > Should I add that to the DT binding or reference the data sheet table since this driver will support 4 different devices > with varying number of outputs from 18-36.
My first thought was to show full table, but four different mappings would add too much noise. So the reference to the data sheet should suffice.
-- Best regards, Jacek Anaszewski
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