From owner-svn-src-all@FreeBSD.ORG Tue Nov 15 21:49:08 2011 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D8A13106566B; Tue, 15 Nov 2011 21:49:08 +0000 (UTC) (envelope-from mdf356@gmail.com) Received: from mail-ey0-f182.google.com (mail-ey0-f182.google.com [209.85.215.182]) by mx1.freebsd.org (Postfix) with ESMTP id 1B7038FC0A; Tue, 15 Nov 2011 21:49:07 +0000 (UTC) Received: by eyd10 with SMTP id 10so8209382eyd.13 for ; Tue, 15 Nov 2011 13:49:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=mFdU7LJAu5j4gomWlb6obiORY1mtiMVbVWH8DL29HDQ=; b=Kw4RQUPMWPOyOPxcjw2NJExx3nmt/fnZFERXN5cjPTHQw2JmxajTv7BQ8sfxmSKCdu bcxcZhvQA4xDys6XUW6J7dgE3knwFmeG3LcYx8r+KvLjW3n0KNdvNqst/fvwaAFrRXUP YR+VHTf0Sj1vvePIuaujE6maYlfKgIWxxdkk8= MIME-Version: 1.0 Received: by 10.68.38.5 with SMTP id c5mr24533443pbk.93.1321393746164; Tue, 15 Nov 2011 13:49:06 -0800 (PST) Sender: mdf356@gmail.com Received: by 10.68.56.97 with HTTP; Tue, 15 Nov 2011 13:49:06 -0800 (PST) In-Reply-To: <201111152222.17549.hselasky@c2i.net> References: <201111152048.pAFKmvNC016452@svn.freebsd.org> <201111152202.24093.hselasky@c2i.net> <201111152222.17549.hselasky@c2i.net> Date: Tue, 15 Nov 2011 13:49:06 -0800 X-Google-Sender-Auth: S0BkyNV8JZbKsGrzRsCs7C15o7w Message-ID: From: mdf@FreeBSD.org To: Hans Petter Selasky Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: "svn-src-head@freebsd.org" , "svn-src-all@freebsd.org" , "src-committers@freebsd.org" Subject: Re: svn commit: r227541 - head/sys/dev/usb/controller X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Nov 2011 21:49:08 -0000 On Tue, Nov 15, 2011 at 1:22 PM, Hans Petter Selasky wro= te: > On Tuesday 15 November 2011 22:20:18 mdf@freebsd.org wrote: >> On Tue, Nov 15, 2011 at 1:02 PM, Hans Petter Selasky > wrote: >> > For USB compliant operation, the USB stack requires hz to be greater o= r >> > equal to 250 hz, to put it like that. Mostly a requirement in USB >> > gadget/device mode. >> >> Really? =A0That's news to me. =A0Is that documented somewhere? =A0I know= we >> still use hz=3D100 internally, but we're on stable/7 still so not using >> the new USB stack yet. > > No it is not documented anywhere. This delay is mostly critical if you en= able > USB power saving features like suspend and resume. Then there are some > software timers which should not derive too much. > > Most of the time the delays in USB are not critical. Transfer timers are = in > the seconds range and that works fine with hz=3D100. > > Where and how should I document such are requirement? > > Add something during system init? > > if (hz < 250) > =A0 printf("USB: hz is too low (ignored)\n"); I'm not sure what functions we have for detecting the OS instance is virtualized, but something like that would be useful if it's really important. Perhaps: "USB: hz value less than 250 may cause functional issues" Thanks, matthew