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

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Date:   Thu, 10 May 2018 14:10:42 -0500
From:   Dan Murphy <dmurphy@...com>
To:     Pavel Machek <pavel@....cz>
CC:     <robh+dt@...nel.org>, <mark.rutland@....com>,
        <jacek.anaszewski@...il.com>, <afd@...com>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-leds@...r.kernel.org>
Subject: Re: [PATCH v5 1/2] dt: bindings: lm3601x: Introduce the lm3601x
 driver

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@...com>
>>
>> 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.
> 
> 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.

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
>>
> 
> 


-- 
------------------
Dan Murphy