Re: [PATCH v5 1/2] dt: bindings: lm3601x: Introduce the lm3601x driver

[Jacek Anaszewski]

Hi Dan,

On 05/10/2018 09:10 PM, Dan Murphy wrote:
> On 05/10/2018 02:06 PM, Dan Murphy wrote:
> > Pavel
> >
> > On 05/10/2018 01:54 PM, Pavel Machek wrote:
> > > Hi!
> > >
> > > > Introduce the device tree bindings for the lm3601x
> > > > family of LED torch, flash and IR drivers.
> > > >
> > > > Signed-off-by: Dan Murphy <dmurphy@xxxxxx>
> > >
> > > Better, thanks.
> > > > +++ b/Documentation/devicetree/bindings/leds/leds-lm3601x.txt
> > > > @@ -0,0 +1,50 @@
> > > > +* Texas Instruments - lm3601x Single-LED Flash Driver
> > >
> > > Ok, so is it single-LED driver, or can it driver ir & white LEDs at
> > > the same time?
> >
> > It is a single LED driver.  It can drive a Torch white LED or IR LED indefinitely or if the driver
> > is programmed to strobe mode the driver will drive the configured LED for the flash timeout specified.
> >
> > Basically a flash and a flash light. IR or White LED.
> >
> >
> > > > +Example:
> > > > +led-controller@64 {
> > > > +	compatible = "ti,lm36010";
> > > > +	#address-cells = <1>;
> > > > +	#size-cells = <0>;
> > > > +	reg = <0x64>;
> > > > +
> > > > +	led@0 {
> > > > +		reg = <0>;
> > > > +		label = "white:torch";
> > > > +		led-max-microamp = <10000>;
> > > > +	};
> > > > +
> > > > +	led@1 {
> > > > +		reg = <1>;
> > > > +		label = "white:flash";
> > > > +		flash-max-microamp = <10000>;
> > > > +		flash-max-timeout-us = <800>;
> > > > +	};
> > >
> > > Is this realistic config? I'd expect flash to use more power than
> > > torch, and would expect longer timeout than 0.8msec.
> >
> > Timeout in the spreadsheet is ms I will update this example and code
> > Current in the spreadsheet is mA I will update this example and code
> >
> > > Also.. if this is physically one white LED, it should not be
> > > spread over reg = <0> and reg = <1>...
> >
> > If the torch LED and strobe LED are the same LED how do I expose them both to the user.
> > It is up to consumer to configure the required interfaces they want to expose to the filesystem.

LED flash class interface is prepared for it.
led_clasdev_flash_register() internally calls led_classdev_register(),
so there is brightness file available for torch related operations.

> > Maybe they don't want the strobe feature and just want LED on/off and switch between IR and White.
> >
> > The IR is driven via a different output pin.
>
> Correction.  There is only one LED drive pin.  The mode selected determines how the device will drive the
> LED.  So you may have one device to drive a Torch and another device to drive the LED.

But only one type of LED can be soldered on the board at a time, right?
If yes, then this is clearly a DT related configuration, and only
one child DT node should be defined for given board.

> Strobe is available in either case but not always required if strobe is not desired by the customer hence
> why I have a separate DT node for it.
>
> Dan
>
> > Dan
> >
> > > Best regards,
> > > 									Pavel

--
Best regards,
Jacek Anaszewski