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

[Hans Petter Selasky]

On 05/24/18 11:59, Edward Napierala wrote:
> 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.
> 

Even though implict, we could specify mA at 5Volt in the sysctl description.

--HPS