linux-kernel - Re: [PATCH v9 4/5] dt-bindings: backlight: Add led-backlight binding

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Message-ID: <CAL_JsqL8b0gWPTt3oJ8ScY_AwP+uB__dZP6Eednfa5Fq9vAptw@mail.gmail.com>
Date:   Tue, 8 Oct 2019 10:00:41 -0500
From:   Rob Herring <robh+dt@...nel.org>
To:     Jean-Jacques Hiblot <jjhiblot@...com>
Cc:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>,
        Sebastian Reichel <sre@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Dan Murphy <dmurphy@...com>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Tomi Valkeinen <tomi.valkeinen@...com>
Subject: Re: [PATCH v9 4/5] dt-bindings: backlight: Add led-backlight binding

On Tue, Oct 8, 2019 at 8:30 AM Jean-Jacques Hiblot <jjhiblot@...com> wrote:
>
> Rob,
>
> On 08/10/2019 14:51, Jean-Jacques Hiblot wrote:
> > Hi Rob,
> >
> > On 07/10/2019 18:15, Rob Herring wrote:
> >> Please send DT bindings to DT list or it's never in my queue. IOW,
> >> send patches to the lists that get_maintainers.pl tells you to.
> >>
> >> On Mon, Oct 7, 2019 at 7:45 AM Jean-Jacques Hiblot <jjhiblot@...com>
> >> wrote:
> >>> Add DT binding for led-backlight.
> >>>
> >>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...com>
> >>> Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>
> >>> Reviewed-by: Sebastian Reichel <sebastian.reichel@...labora.com>
> >>> ---
> >>>   .../bindings/leds/backlight/led-backlight.txt | 28
> >>> +++++++++++++++++++
> >>>   1 file changed, 28 insertions(+)
> >>>   create mode 100644
> >>> Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> >> Please make this a DT schema.
> >
> > OK.
> >
> > BTW I used "make dt_binding_check" but had to fix a couple of YAMLs
> > file to get it to work. Do you have a kernel tree with already all the
> > YAML files in good shape ? Or do you want me to post the changes to
> > devicetree@...r.kernel.org ?
> >
> >
> >>
> >>> diff --git
> >>> a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> >>> b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> >>> new file mode 100644
> >>> index 000000000000..4c7dfbe7f67a
> >>> --- /dev/null
> >>> +++
> >>> b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> >>> @@ -0,0 +1,28 @@
> >>> +led-backlight bindings
> >>> +
> >>> +This binding is used to describe a basic backlight device made of
> >>> LEDs.
> >>> +It can also be used to describe a backlight device controlled by
> >>> the output of
> >>> +a LED driver.
> >>> +
> >>> +Required properties:
> >>> +  - compatible: "led-backlight"
> >>> +  - leds: a list of LEDs
> >> 'leds' is already used as a node name and mixing is not ideal.
> >>
> >> We already have 'flash-leds' in use and with the same definition, so
> >> lets continue that and use 'backlight-leds'.
> > OK
>
> I am taking that back. I have added of_get_led() and devm_of_get_led()
> to the LED core to make it easier to get a LED from the DT. I modeled
> the interface like it is done for PWM, PHYs or clocks. The property
> containing list/array of phandle  is always named the same. To get one
> particular PWM/PHY/clock, a identifier (name or integer) must be provided.

It can be done as we do support that with '-gpios', but yes, it is a
bit more painful to deal with.

> So unless there is a strong incentive to do otherwise I's rather keep
> this name here.

In that case, this needs to be documented as a common LED binding, not
something hidden away in this binding.

Rob