On 08/21/2013 02:29 AM, Jacek Anaszewski wrote: > On 08/20/2013 06:20 PM, Stephen Warren wrote: >> On 08/19/2013 11:54 PM, Jonathan Cameron wrote: >>> Stephen Warren<swarren-3lzwWm7+Weoh9ZMKESR00Q@xxxxxxxxxxxxxxxx> wrote: >>>> On 08/16/2013 07:12 AM, Jacek Anaszewski wrote: >>>>> This patch adds device tree binding documentation >>>>> for the gp2ap020a00f proximity/als sensor. >>>> >>>>> diff --git >>>>> a/Documentation/devicetree/bindings/iio/light/gp2ap020a00f.txt >>>>> +* Sharp GP2AP020A00F I2C Proximity/ALS sensor >>>>> + >>>>> +Required properties: >>>>> + >>>>> + - compatible : should be "sharp,gp2ap020a00f" >>>>> + - reg : the I2C address of the light sensor >>>>> + - interrupt-parent : phandle to the parent interrupt controller >>>>> + - interrupts : should be INT interrupt pin >>>>> + - vled-supply : VLED power supply, as covered >>>>> + in >>>>> Documentation/devicetree/bindings/regulator/regulator.txt >>>> >>>> If this is a sensor for proximity and light, why does it need a >>>> regulator for an LED? >>> >>> This type of proximity sensor uses reflected light from an led right >>> next to it to detect something is nearby. The devices typically >>> either integrate the led directly or control an external led. >> >> OK, that makes sense. It might make sense to briefly describe this >> aspect of the HW at the top of the binding file. Perhaps something like: >> >> ---------- >> * Sharp GP2AP020A00F I2C Proximity/ALS sensor >> >> The proximity detector sensor requires an associated LED for its >> operation. The power supply to this LED is also defined by this binding. >> ---------- >> >> ? > > Actually the LED is built-in into the chip, and its anode is exposed > on the LEDA pin. On the board I have for my disposal the presence of > this voltage is driven by some circuit. It doesn't have to be the > case for all boards, as the presence of the voltage alone doesn't > drive the state of the diode - the relevant device register has to > be set to activate/deactivate it. Having this in mind we must prepare > for the cases where the voltage will be attached directly to the > LEDA pin without any intermediary driving circuit. > > To handle this situation an empty regulator node should be assigned > to the vled-supply property. I am not sure whether this case should > be mentioned in the description. I will assume that it is obvious. Historically, all regulator supplies have been mandatory; in other words, if a device might ever need a voltage regulator, then the DT property to define it was mandatory, and it could be implemented either by a "real" regulator or a non-switchable fixed regulator. More recently, there's been some work to support optional regulators, such that the DT supply property can either point at a "real" regulator, or simply be missing. I'm not sure what the state of that change is in the regulator tree though, although in terms of the DT binding, I guess you should be able to make the property optional now if you want. > In view of the above I would change the description to: > > ---------- > * Sharp GP2AP020A00F I2C Proximity/ALS sensor > > The proximity detector sensor requires power supply for its > built-in LED. It is also defined by this binding. > > ---------- > > What is your opinion? That sounds good. -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
