From owner-freebsd-arm@FreeBSD.ORG Tue Oct 1 13:12:55 2013 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 8A706FDD; Tue, 1 Oct 2013 13:12:55 +0000 (UTC) (envelope-from paul@gromit.dlib.vt.edu) Received: from lennier.cc.vt.edu (lennier.cc.vt.edu [198.82.162.213]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 496952A0E; Tue, 1 Oct 2013 13:12:54 +0000 (UTC) Received: from mr2.cc.vt.edu (mr2.cc.vt.edu [198.82.163.74]) by lennier.cc.vt.edu (8.13.8/8.13.8) with ESMTP id r91DCARQ032344; Tue, 1 Oct 2013 09:12:10 -0400 Received: from auth1.smtp.vt.edu (auth1.smtp.vt.edu [198.82.161.152]) by mr2.cc.vt.edu (8.14.4/8.14.4) with ESMTP id r91DCAD4030418; Tue, 1 Oct 2013 09:12:10 -0400 Received: from pmather.tower.lib.vt.edu (pmather.tower.lib.vt.edu [128.173.51.28]) (authenticated bits=0) by auth1.smtp.vt.edu (8.14.4/8.14.4) with ESMTP id r91DCAOt032485 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Tue, 1 Oct 2013 09:12:10 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) Subject: Re: BBB CPU clock (was: Re: FreeBSD on Cubieboard 2, UDOO and Galaxy Note 10.1 (Exynos). From: Paul Mather In-Reply-To: Date: Tue, 1 Oct 2013 09:12:10 -0400 Content-Transfer-Encoding: quoted-printable Message-Id: <603C57BE-8DCE-4178-B912-DBBB5CAC93B3@gromit.dlib.vt.edu> References: To: Jia-Shiun Li X-Mailer: Apple Mail (2.1510) Cc: "freebsd-arm@freebsd.org" , ticso@cicely.de X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Porting FreeBSD to the StrongARM Processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Oct 2013 13:12:55 -0000 On Sep 30, 2013, at 5:04 PM, Jia-Shiun Li wrote: > On Mon, Sep 30, 2013 at 11:26 AM, Tim Kientzle = wrote: >>=20 >> My understanding: >>=20 >> * We should query the PMIC to determine whether we're running from = 5V supply or USB. >>=20 >> * Based on that, we should adjust the CPU clocks. We should be = able to run 1GHz from 5v supply. >>=20 >> Connecting cpufreq would be a nice addition. >=20 > Hi Tim, >=20 > Yes you are right. I digged a bit the PMIC docs. > I didn't realize that DCDC2/3 output to MPC/core are adjustable. >=20 > The PMIC capped USB input at 500mA by default, so if not changed = otherwise, > or to be safe with what most USB power supplies are, it is correct to = only go up > to 1GHz on DC input. >=20 > I played for a while manually setting PMIC from u-boot prompt, setting = MPU volt > to 1.325v, raise USB current limit, etc. but still cannot get it run > above 800MHz. > It always stopped booting at initing uhub. Looks like I need a bigger > DC adapter. What 5V adapter are you using? The one recommended by Adafruit for the = BeagleBone Black is a 5V 2A adapter. The BBB system reference manual = states, "A 5VDC supply can be used to provide power to the board. The = power supply current depends on how many and what type of add-on boards = are connected to the board. For typical use, a 5VDC supply rated at 1A = should be sufficient. If heavier use of the expansion headers or USB = host port is expected, then a higher current supply will be required." = The BBB Wiki = (http://circuitco.com/support/index.php?title=3DBeagleBoneBlack) lists = the power consumption of the BBB itself as 210--460 mA@5V depending on = "activity and processor speed." I believe if you use capes with the BBB = then you need to use the external PSU. I've personally found the BBB to be a bit flaky when run via the USB OTG = connector. I prefer to run it via a 5V external PSU for stable = operation. Cheers, Paul.