Re: [PATCH/RFC v9 06/19] DT: Add documentation for the mfd Maxim max77693

[Sakari Ailus <sakari.ailus@iki.fi>]

Hi Jacek,

On Wed, Dec 03, 2014 at 05:06:41PM +0100, Jacek Anaszewski wrote:
> This patch adds device tree binding documentation for
> the flash cell of the Maxim max77693 multifunctional device.
> 
> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Chanwoo Choi <cw00.choi@samsung.com>
> Cc: Bryan Wu <cooloney@gmail.com>
> Cc: Richard Purdie <rpurdie@rpsys.net>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Pawel Moll <pawel.moll@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
> Cc: Kumar Gala <galak@codeaurora.org>
> Cc: <devicetree@vger.kernel.org>
> ---
>  Documentation/devicetree/bindings/mfd/max77693.txt |   89 ++++++++++++++++++++
>  1 file changed, 89 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mfd/max77693.txt b/Documentation/devicetree/bindings/mfd/max77693.txt
> index 01e9f30..25a6e78 100644
> --- a/Documentation/devicetree/bindings/mfd/max77693.txt
> +++ b/Documentation/devicetree/bindings/mfd/max77693.txt
> @@ -41,7 +41,66 @@ Optional properties:
>  	 To get more informations, please refer to documentaion.
>  	[*] refer Documentation/devicetree/bindings/pwm/pwm.txt
>  
> +- led : the LED submodule device node
> +
> +There are two led outputs available - fled1 and fled2. Each of them can
> +control a separate led or they can be connected together to double
> +the maximum current for a single connected led. One led is represented
> +by one child node.
> +
> +Required properties:
> +- compatible : Must be "maxim,max77693-led".
> +
> +Optional properties:
> +- maxim,fleds : Array of current outputs in order: fled1, fled2.
> +	Note: both current outputs can be connected to a single led
> +	Possible values:
> +		MAX77693_LED_FLED_UNUSED - the output is left disconnected,
> +		MAX77693_LED_FLED_USED - a diode is connected to the output.

As you have a LED sub-nodes for each LED already, isn't this redundant?

> +- maxim,trigger-type : Array of trigger types in order: flash, torch.
> +	Possible trigger types:
> +		MAX77693_LED_TRIG_TYPE_EDGE - Rising edge of the signal triggers
> +			the flash/torch,
> +		MAX77693_LED_TRIG_TYPE_LEVEL - Signal level controls duration of

How about: "Strobe pulse length ..."?

How long does the torch stay on if you use edge trigger for it? I've always
thought the torch enable pin was a practical joke. :-)

If you need it this for torch as well, I'd use separate properties for the
purpose, i.e. trigger-type-flash and trigger-type-torch.

> +			the flash/torch.
> +- maxim,trigger : Array of flags indicating which trigger can activate given led
> +	in order: fled1, fled2.
> +	Possible flag values (can be combined):
> +		MAX77693_LED_TRIG_FLASHEN - FLASHEN pin of the chip,
> +		MAX77693_LED_TRIG_TORCHEN - TORCHEN pin of the chip,
> +		MAX77693_LED_TRIG_SOFTWARE - software via I2C command.

Is there a need to prevent strobing using a certain method? Just wondering.

> +- maxim,boost-mode :
> +	In boost mode the device can produce up to 1.2A of total current
> +	on both outputs. The maximum current on each output is reduced
> +	to 625mA then. If there are two child led nodes defined then boost
> +	is enabled by default.
> +	Possible values:
> +		MAX77693_LED_BOOST_OFF - no boost,
> +		MAX77693_LED_BOOST_ADAPTIVE - adaptive mode,
> +		MAX77693_LED_BOOST_FIXED - fixed mode.
> +- maxim,boost-vout : Output voltage of the boost module in millivolts.
> +- maxim,vsys-min : Low input voltage level in millivolts. Flash is not fired
> +	if chip estimates that system voltage could drop below this level due
> +	to flash power consumption.
> +
> +Required properties of the LED child node:
> +- label : see Documentation/devicetree/bindings/leds/common.txt
> +- maxim,fled_id : Identifier of the fled output the led is connected to;

I'm pretty sure this will be needed for about every chip that can drive
multiple LEDs. Shouldn't it be documented in the generic documentation?

> +		MAX77693_LED_FLED1 - FLED1 output of the device - it has to be
> +			used also if a single LED is connected to both outputs,
> +		MAX77693_LED_FLED2 - FLED2 output of the device.
> +
> +Optional properties of the LED child node:
> +- max-microamp : see Documentation/devicetree/bindings/leds/common.txt
> +		Range: 15625 - 250000
> +- flash-max-microamp : see Documentation/devicetree/bindings/leds/common.txt
> +		Range: 15625 - 1000000
> +- flash-timeout-microsec : see Documentation/devicetree/bindings/leds/common.txt
> +		Range: 62500 - 1000000
> +
>  Example:
> +#include <dt-bindings/mfd/max77693.h>
> +
>  	max77693@66 {
>  		compatible = "maxim,max77693";
>  		reg = <0x66>;
> @@ -73,4 +132,34 @@ Example:
>  			pwms = <&pwm 0 40000 0>;
>  			pwm-names = "haptic";
>  		};
> +
> +		led {
> +			compatible = "maxim,max77693-led";
> +			maxim,fleds = <MAX77693_LED_FLED_USED
> +				       MAX77693_LED_FLED_USED>;
> +			maxim,trigger = <MAX77693_LED_TRIG_ALL
> +					 (MAX77693_LED_TRIG_TORCHEN |
> +					 MAX77693_LED_TRIG_SOFTWARE)>;
> +			maxim,trigger-type = <MAX77693_LED_TRIG_TYPE_EDGE
> +					      MAX77693_LED_TRIG_TYPE_LEVEL>;
> +			maxim,boost-mode = <MAX77693_LED_BOOST_ADAPTIVE>;
> +			maxim,boost-vout = <5000>;
> +			maxim,vsys-min = <2400>;
> +
> +			camera1_flash: led1 {
> +				maxim,fled_id = <MAX77693_LED_FLED1>;
> +				label = "max77693-flash1";
> +				max-microamp = <250000>;
> +				flash-max-microamp = <625000>;
> +				flash-timeout-microsec = <1000000>;
> +			};
> +
> +			camera2_flash: led2 {
> +				maxim,fled_id = <MAX77693_LED_FLED2>;
> +				label = "max77693-flash2";
> +				max-microamp = <250000>;
> +				flash-max-microamp = <500000>;
> +				flash-timeout-microsec = <1000000>;
> +			};
> +		};

I like how this looks like in general.

>  	};

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus@iki.fi	XMPP: sailus@retiisi.org.uk