From owner-svn-src-head@freebsd.org Thu May 24 10:01:32 2018 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id DD5ACEAA76D; Thu, 24 May 2018 10:01:32 +0000 (UTC) (envelope-from hps@selasky.org) Received: from mail.turbocat.net (turbocat.net [IPv6:2a01:4f8:c17:6c4b::2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 7658580FD4; Thu, 24 May 2018 10:01:32 +0000 (UTC) (envelope-from hps@selasky.org) Received: from hps2016.home.selasky.org (unknown [62.141.128.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.turbocat.net (Postfix) with ESMTPSA id A411B26038C; Thu, 24 May 2018 12:01:30 +0200 (CEST) Subject: Re: svn commit: r334115 - in head: share/man/man4 sys/dev/usb/template To: Edward Napierala , "H. Schmalzbauer - OmniLAN" Cc: Ravi Pokala , src-committers , svn-src-all@freebsd.org, svn-src-head@freebsd.org References: <201805232006.w4NK64jS044384@repo.freebsd.org> <9B0033E1-56EC-4CA0-BC28-056871B32B0A@panasas.com> From: Hans Petter Selasky Message-ID: <94801dec-73b4-63f3-6f01-b0e175073d6e@selasky.org> Date: Thu, 24 May 2018 12:01:19 +0200 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 May 2018 10:01:33 -0000 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, 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