linux-kernel - Re: [PATCH v2 1/2] leds: ncp5623: Add device tree binding documentation

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Date:	Tue, 28 Jun 2016 15:56:59 -0500
From:	Rob Herring <robh@...nel.org>
To:	Jacek Anaszewski <j.anaszewski@...sung.com>
Cc:	Florian Vaussard <florian.vaussard@...il.com>,
	devicetree@...r.kernel.org, Richard Purdie <rpurdie@...ys.net>,
	Mark Rutland <mark.rutland@....com>,
	Pavel Machek <pavel@....cz>, linux-leds@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Florian Vaussard <florian.vaussard@...g-vd.ch>
Subject: Re: [PATCH v2 1/2] leds: ncp5623: Add device tree binding
 documentation

On Mon, Jun 27, 2016 at 10:11:04AM +0200, Jacek Anaszewski wrote:
> Hi Florian,
> 
> On 06/27/2016 09:03 AM, Florian Vaussard wrote:
> >Add device tree binding documentation for On Semiconductor NCP5623 I2C
> >LED driver. The driver can independently control the PWM of the 3
> >channels with 32 levels of intensity.
> >
> >The current delivered by the current source can also be controlled. To
> >do so, the led-max-microamp property is used by each LED sub-node. The
> >maximum value is then found and used as a limit to compute the final
> >intensity of the current source. If a LED happens to have a lower limit,
> >the PWM is then used to limit the current to the requested value.
> >
> >In order to control the current source, it is also necessary to know
> >the current on the Iref pin, hence the onnn,led-iref-microamp property.
> >It is usually set using an external bias resistor, following
> >Iref = Vref/Rbias with Vref=0.6V.
> >
> >Signed-off-by: Florian Vaussard <florian.vaussard@...g-vd.ch>
> >---
> >  .../devicetree/bindings/leds/leds-ncp5623.txt      | 60 ++++++++++++++++++++++
> >  1 file changed, 60 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/leds/leds-ncp5623.txt
> >
> >diff --git a/Documentation/devicetree/bindings/leds/leds-ncp5623.txt b/Documentation/devicetree/bindings/leds/leds-ncp5623.txt
> >new file mode 100644
> >index 0000000..77dd7ad
> >--- /dev/null
> >+++ b/Documentation/devicetree/bindings/leds/leds-ncp5623.txt
> >@@ -0,0 +1,60 @@
> >+* ON Semiconductor - NCP5623 3-Channel LED Driver
> >+
> >+The NCP5623 is a 3-channel I2C LED driver. The brightness of each
> >+channel can be independently set using 32 levels. Each LED is represented
> >+as a sub-node of the device.
> >+
> >+Required properties:
> >+  - compatible: Should be "onnn,ncp5623"
> >+  - reg: I2C slave address (fixed to 0x38)
> >+  - #address-cells: must be 1
> >+  - #size-cells: must be 0
> >+  - onnn,led-iref-microamp: Current on the Iref pin in microampere. It depends
> >+    on the value of the external bias resistor Rbias, following
> >+    Iref = Vref / Rbias with Vref = 0.6V. This is used to set the intensity of
> >+    the current that can be provided by the internal current source, based on
> >+    the maximum current permitted by LED sub-nodes (see below), but no more than
> >+    Imax = 2400 * Iref.
> >+
> >+LED sub-nodes
> >+=============
> >+
> >+Required properties:
> >+  - reg : LED channel number (0..2)
> >+  - led-max-microamp: Maximum allowable current inside the LED in microampere.
> >+    This property is used to limit the PWM ratio, based on the intensity of the
> >+    internal current source (see above).
> >+
> >+Optional properties:
> >+  - label: Used for naming LEDs
> 
> Instead of the above description use same reference to common led
> bindings as below.
> 
> >+  - default-trigger: see Documentation/devicetree/bindings/leds/common.txt

And this is missing the linux prefix.