Date: Thu, 24 May 2018 19:02:27 +0100 From: Edward Napierala <trasz@freebsd.org> To: Hans Petter Selasky <hps@selasky.org> Cc: "H. Schmalzbauer - OmniLAN" <h.schmalzbauer@omnilan.de>, Ravi Pokala <rpokala@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r334115 - in head: share/man/man4 sys/dev/usb/template Message-ID: <CAFLM3-okddyNZ3GD7Qwo%2B=oJ9-7qu_7iKozPzn9RYhk2MmvocA@mail.gmail.com> In-Reply-To: <94801dec-73b4-63f3-6f01-b0e175073d6e@selasky.org> References: <201805232006.w4NK64jS044384@repo.freebsd.org> <9B0033E1-56EC-4CA0-BC28-056871B32B0A@panasas.com> <fa8a13c4-c1ed-0b23-6c2e-3e23ecfe8137@omnilan.de> <CAFLM3-r2VmtjeSOe6bPJ1kPumvY=GRRm45s5kQ88s3zXv-cH3Q@mail.gmail.com> <94801dec-73b4-63f3-6f01-b0e175073d6e@selasky.org>
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2018-05-24 11:01 GMT+01:00 Hans Petter Selasky <hps@selasky.org>: > On 05/24/18 11:59, Edward Napierala wrote: > >> 2018-05-24 8:41 GMT+01:00 H. Schmalzbauer - OmniLAN < >> h.schmalzbauer@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, speaki= ng >>> of "power" while refering to current seems valid to me =E2=80=93 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=C2=A2 >>> >>> >> 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!
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