svn commit: r334115 - in head: share/man/man4 sys/dev/usb/template

[Edward Napierala]

2018-05-24 8:41 GMT+01:00 H. Schmalzbauer - OmniLAN <
h.schmalzbauer at omnilan.de>:

> Am 23.05.2018 um 22:35 schrieb Ravi Pokala:
>
>> Hi Traz,
>>
>> You're referring to power consumption in terms of (milli)Amps. That's not
>> right; power is measured in Watts. What you're actually talking about is
>> *current*. And it looks like in some situations USB devices can draw more
>> than 500mA.
>>
>
> Since the voltage isn't a variable when talking about USB power, speaking
> of "power" while refering to current seems valid to me – it's 5 V only and
> those who read that don't even need to do any math in head.
> I never read 2500mW in USB world, 500mA is common.
> Just my 2¢
>

I've just did some googling, and it seems you're right - while from physics
point of view mA is definitely current and not power, pretty much
everywhere I look the USB power (reported in bMaxPower) is specified in mA,
not mW.  Thus, I'm leaning toward leaving it as it is - wrong from a
physics point of view, but aligned with the the USB naming convention.