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

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Message-ID: <20180808214527.GE15831@amd>
Date:   Wed, 8 Aug 2018 23:45:27 +0200
From:   Pavel Machek <pavel@....cz>
To:     Dan Murphy <dmurphy@...com>
Cc:     robh+dt@...nel.org, jacek.anaszewski@...il.com,
        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

On Wed 2018-08-08 16:41:16, Dan Murphy wrote:
> On 08/08/2018 04:09 PM, Pavel Machek wrote:
> > On Wed 2018-08-08 16:04:43, 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.
> > 
> > Yes, and LED strings are statically assigned to banks, right?
> > 
> > So why not simply forget about LED strings for sake of hw
> > abstractions, and work just with banks?
> 
> How would you set the control bank register for the correct LED string configuration?

Have property at each LED saying which which HVLEDs it controls?

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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