linux-kernel - Re: [PATCH 1/2] dt-bindings: trivial: add ti,lm3630a binding

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Date:   Fri, 30 Nov 2018 09:25:40 -0500
From:   Brian Masney <masneyb@...tation.org>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Daniel Thompson <daniel.thompson@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-fbdev@...r.kernel.org, devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        Craig Tatlor <ctatlor97@...il.com>, Dan Murphy <dmurphy@...com>
Subject: Re: [PATCH 1/2] dt-bindings: trivial: add ti,lm3630a binding

On Fri, Nov 30, 2018 at 08:13:04AM -0600, Rob Herring wrote:
> > > It's quite unusual for a backlight device to have a trivial binding.
> > >
> > > The driver supports fairly extensive parametrization via struct
> > > lm3530a_platform_data. It is really the case that none of these
> > > properties should ever be set via DT?
> >
> > Hi Daniel,
> >
> > I initially assumed that we would let user space configure these values
> > once the system has booted, but you are right that these should be
> > available in device tree.
> >
> > The driver has two different LED banks that can be configured
> > independently.
> 
> That is usually represented with child nodes which makes this anything
> but trivial. Plus, given that we have bindings for LEDs/backlights, no
> LED/backlight controller is a trivial device.

Hi Rob,

I agree and I'm not going to use a trivial binding for v2. See below for
some questions that I have from my last email.


> > How do you feel about having a single property in
> > device tree populate the initial values for both banks? I propose that
> > we could use the property default-brightness-level for leda_init_brt
> > and ledb_init_brt in struct lm3630a_platform_data. The max-brightness
> > property can populate leda_max_brt and ledb_max_brt.
> >
> > I need to look at other bindings this weekend to see if there are any
> > standard properties that I can use for leda_ctrl/ledb_ctrl, pwm_ctrl,
> > and pwm_period.
> >
> > Brian
> >