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

[Edward Napierala]

2018-05-24 11:01 GMT+01:00 Hans Petter Selasky <hps at selasky.org>:

> 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.


Good idea, done!