Messages in this thread | | | Date | Wed, 7 Dec 2011 16:00:02 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] leds: driver for ab5500 high voltage leds |
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On Wed, 07 Dec 2011 20:01:46 +0200 Denis Kuzmenko <linux@solonet.org.ua> wrote:
> > The three channels are indeed high-voltage LEDs, they supply > > up to 20V from a supply voltage of some standard mobile handset > > battery at say 3.8 V or so. But there is no register to control the > > voltage or anything like that. > > > > My naive understanding is that you set the current limit and then > > the HV transformer (I guess this is a buck converter of some kind) > > will raise the voltage level until it either (A) cannot raise it any more > > at c:a 20V or (b) the current limit is reached. > > > > I suspect this is because for LEDs of this type you get a > > specified current but the voltage just has to be "high enough" > > to break through some diode barrier threshold or so. After > > that intensity is controlled by limiting the current. > > > > Does this suffice as explanation...? > > > > Yours, > > Linus Walleij > > Yeah, It does, thank you. > Does it worth to make additional comment in code to avoid further questions?
Yes, I think that the fact that a reviewer asked a question such as this is a reliable sign that subsequent readers will be wondering the same thing, so it is an "oops it needs a comment" signal.
I won't do anything with this patch yet - I'm waiting to see if Mark stops being surprised ;)
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