Re: [PATCH V6 3/8] backlight: qcom-wled: Add new properties for PMI8998

[kgunda@xxxxxxxxxxxxxx]

On 2019-10-01 20:42, Dan Murphy wrote:
> Kiran
>
> On 9/30/19 1:39 AM, Kiran Gunda wrote:
> > Update the bindings with the new properties used for
> > PMI8998.
> >
> > Signed-off-by: Kiran Gunda <kgunda@xxxxxxxxxxxxxx>
> > Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > Acked-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
> > ---
> >   .../bindings/leds/backlight/qcom-wled.txt          | 76 
> > ++++++++++++++++++----
> >   1 file changed, 62 insertions(+), 14 deletions(-)
> >
> > diff --git 
> > a/Documentation/devicetree/bindings/leds/backlight/qcom-wled.txt 
> > b/Documentation/devicetree/bindings/leds/backlight/qcom-wled.txt
> > index 14f28f2..9d840d5 100644
> > --- a/Documentation/devicetree/bindings/leds/backlight/qcom-wled.txt
> > +++ b/Documentation/devicetree/bindings/leds/backlight/qcom-wled.txt
> > @@ -20,8 +20,7 @@ platforms. The PMIC is connected to the host 
> > processor via SPMI bus.
> >   - default-brightness
> >   	Usage:        optional
> >   	Value type:   <u32>
> > -	Definition:   brightness value on boot, value from: 0-4095
> > -		      Default: 2048
> > +	Definition:   brightness value on boot, value from: 0-4095.
> >     - label
> >   	Usage:        required
> > @@ -48,20 +47,24 @@ platforms. The PMIC is connected to the host 
> > processor via SPMI bus.
> >   - qcom,current-limit
> >   	Usage:        optional
> >   	Value type:   <u32>
> > -	Definition:   mA; per-string current limit
> > -		      value: For pm8941: from 0 to 25 with 5 mA step
> > -			     Default 20 mA.
> > -			     For pmi8998: from 0 to 30 with 5 mA step
> > -			     Default 25 mA.
> > +	Definition:   mA; per-string current limit; value from 0 to 25 with
> > +		      1 mA step.
> > +		      This property is supported only for pm8941.
> > +
> > +- qcom,current-limit-microamp
> > +	Usage:        optional
> > +	Value type:   <u32>
> > +	Definition:   uA; per-string current limit; value from 0 to 30000 
> > with
> > +		      2500 uA step.
> >     - qcom,current-boost-limit
> >   	Usage:        optional
> >   	Value type:   <u32>
> >   	Definition:   mA; boost current limit.
> >   		      For pm8941: one of: 105, 385, 525, 805, 980, 1260, 1400,
> > -		      1680. Default: 805 mA
> > +		      1680.
> >   		      For pmi8998: one of: 105, 280, 450, 620, 970, 1150, 1300,
> > -		      1500. Default: 970 mA
> > +		      1500.
> >     - qcom,switching-freq
> >   	Usage:        optional
> > @@ -69,22 +72,66 @@ platforms. The PMIC is connected to the host 
> > processor via SPMI bus.
> >   	 Definition:   kHz; switching frequency; one of: 600, 640, 685, 
> > 738,
> >   		       800, 872, 960, 1066, 1200, 1371, 1600, 1920, 2400, 3200,
> >   		       4800, 9600.
> > -		       Default: for pm8941: 1600 kHz
> > -				for pmi8998: 800 kHz
> >     - qcom,ovp
> >   	Usage:        optional
> >   	Value type:   <u32>
> >   	Definition:   V; Over-voltage protection limit; one of:
> > -		      27, 29, 32, 35. default: 29V
> > +		      27, 29, 32, 35.
> >   		      This property is supported only for PM8941.
> >   +- qcom,ovp-millivolt
> > +	Usage:        optional
> > +	Value type:   <u32>
> > +	Definition:   mV; Over-voltage protection limit;
> > +		      For pmi8998: one of 18100, 19600, 29600, 31100
> > +		      If this property is not specified for PM8941, it
> > +		      falls back to "qcom,ovp" property.
> > +
> >   - qcom,num-strings
> >   	Usage:        optional
> >   	Value type:   <u32>
> >   	Definition:   #; number of led strings attached;
> > -		      value from 1 to 3. default: 2
> > -		      This property is supported only for PM8941.
> > +		      value: For PM8941 from 1 to 3.
> > +			     For PMI8998 from 1 to 4.
>
> We probably don't need this since we define 1 led node per output. 
> And if you need to define
>
> multiple strings per node then you use led-sources.
>
> Then you will use fwnode_property_count_u32(child, "led-sources"); to
> get the number of outputs
I have kept this property as is to have the backward compatibility with 
pm8941-wled.
The backward compatibility is broken if this property is removed.

> > +
> > +- interrupts
> > +	Usage:        optional
> > +	Value type:   <prop encoded array>
> > +	Definition:   Interrupts associated with WLED. This should be
> > +		      "short" and "ovp" interrupts. Interrupts can be
> > +		      specified as per the encoding listed under
> > +		      Documentation/devicetree/bindings/spmi/
> > +		      qcom,spmi-pmic-arb.txt.
> > +
> > +- interrupt-names
> > +	Usage:        optional
> > +	Value type:   <string>
> > +	Definition:   Interrupt names associated with the interrupts.
> > +		      Must be "short" and "ovp". The short circuit detection
> > +		      is not supported for PM8941.
> > +
> > +- qcom,enabled-strings
> > +	Usage:        optional
> > +	Value tyoe:   <u32 array>
> > +	Definition:   Array of the WLED strings numbered from 0 to 3. Each
> > +		      string of leds are operated individually. Specify the
> > +		      list of strings used by the device. Any combination of
> > +		      led strings can be used.
>
> We usually use the reg property per led node to denote what output is
> associated with which
>
> property node.  And if you want to define multiple outputs per node
> then you need to use
>
> led-sources
>
> See leds-lm3697.txt for an example
>
> Dan
As per the Qualcomm hardware recommendation , all the strings (leds) 
properties like
OVP, FSC and brightness etc .. should have the same values. That's why 
all the strings (leds)
and it's properties are mentioned in a single node.