linux-kernel - Re: [PATCH v2 1/2] dt: bindings: lm3697: Add bindings for lm3697 driver

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Date:   Wed, 8 Aug 2018 23:09:49 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, Pavel Machek <pavel@....cz>
Cc:     robh+dt@...nel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [PATCH v2 1/2] dt: bindings: lm3697: Add bindings for lm3697
 driver

Hi Dan,

On 08/08/2018 11:04 PM, Dan Murphy wrote:
> On 08/08/2018 04:02 PM, Pavel Machek wrote:
>> Hi!
>>
>>>>> +	- #size-cells : 0
>>>>> +	- control-bank-cfg - : Indicates which sink is connected to which control bank
>>>>> +		0 - All HVLED outputs are controlled by bank A
>>>>> +		1 - HVLED1 is controlled bank B, HVLED2/3 are controlled by bank A
>>>>> +		2 - HVLED2 is controlled bank B, HVLED1/3 are controlled by bank A
>>>>> +		3 - HVLED1/2 are controlled by bank B, HVLED3 is controlled by bank A
>>>>> +		4 - HVLED3 is controlled by bank B, HVLED1/2 are controlled by bank A
>>>>> +		5 - HVLED1/3 is controlled by bank B, HVLED2 is controlled by bank A
>>>>> +		6 - (default) HVLED1 is controlled by bank A, HVLED2/3 are controlled by bank B
>>>>> +		7 - All HVLED outputs are controlled by bank B
>>>>
>>>> This is quite long way to describe a bitmask, no? Could we make
>>>> it so that control-bank-cfg is not needed?
>>>
>>> The problem we have here is there is a potential to control
>>> 3 different LED string but only 2 sinks.  So control bank A can control 2 LED strings and control
>>> bank b can control 1 LED string.  
>>>
>>
>> Can we forget about the LED strings, and just expose the sinks as
>> Linux LED devices?
> 
> 2 sinks 3 LED strings.  How do you know which LED string is which and what bank it belongs
> to when setting the brightness.  Each Bank has a separate register for brightness control.

Just a blind shot, without going into details - could you please check
if led-sources property documented in the common LED bindings couldn't
help here?

-- 
Best regards,
Jacek Anaszewski