From martinjonestechnology@googlemail.com Thu Sep 17 09:15:46 2009 Received: from fg-out-1718.google.com ([72.14.220.154]) by stoneboat.aleph1.co.uk with esmtp (Exim 4.69) (envelope-from ) id 1MoC9U-0000qx-S3 for balloon@balloonboard.org; Thu, 17 Sep 2009 09:15:46 +0100 Received: by fg-out-1718.google.com with SMTP id 22so99864fge.7 for ; Thu, 17 Sep 2009 01:15:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:received:received:sender:message-id:date:from :organization:user-agent:mime-version:to:subject:references :in-reply-to:content-type:content-transfer-encoding; bh=vJydfmG0B8JE/3Opy/68b85KF6/RZoRazrz//RUP5+4=; b=JvbR/HEhqy6LbdHR5u9o4kv40N3kFtYLOJBbkJDKpOdOQSHwoZDF783PeDZ1DEKyM7 sdYU0kZGYnbvqYFRCTXHrQ8AfwFZpCNwxyqtBpv7v41beP6xU7Ik2Di4Z2uQI5X/2ggK ZCG8OBhnoiCpjup1q8xO61Nu7GdhgPng5I7eA= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=sender:message-id:date:from:organization:user-agent:mime-version:to :subject:references:in-reply-to:content-type :content-transfer-encoding; b=ggC+QK0EyHLw2F5R6mQlw5Qoiq18q/UYR+N27zQ8mg7TRM151h5AZQc64KrQqpkj4V hJ2hT3UeujxwHoGJ2J1JQ2/NaBOsZvpKQ+qgvU6JZRwkOnriK1fzvCjGbWYLZqqjQx5g bdn8rSYyGdTWSd13wz3XtKhYqX2QLb3GQ4X4w= Received: by 10.86.222.15 with SMTP id u15mr272029fgg.33.1253175338863; Thu, 17 Sep 2009 01:15:38 -0700 (PDT) Received: from ?192.168.1.8? (cpc6-cmbg1-0-0-cust874.cmbg.cable.ntl.com [82.10.239.107]) by mx.google.com with ESMTPS id 12sm605278fgg.5.2009.09.17.01.15.36 (version=TLSv1/SSLv3 cipher=RC4-MD5); Thu, 17 Sep 2009 01:15:36 -0700 (PDT) Sender: Chris Jones Message-ID: <4AB1F027.3050508@martin-jones.com> Date: Thu, 17 Sep 2009 09:15:35 +0100 From: Chris Jones Organization: Martin-Jones Technology Ltd User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: balloon@balloonboard.org References: <4AB15387.6060805@martin-jones.com> <20090916231745.GS8124@dream.aleph1.co.uk> In-Reply-To: <20090916231745.GS8124@dream.aleph1.co.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 72.14.220.154 X-SA-Exim-Mail-From: martinjonestechnology@googlemail.com X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on stoneboat.aleph1.co.uk X-Spam-Level: X-Spam-Status: No, score=-2.4 required=4.5 tests=AWL,BAYES_00,SPF_PASS autolearn=no version=3.2.5 X-SA-Exim-Version: 4.2.1 (built Wed, 25 Jun 2008 17:14:11 +0000) X-SA-Exim-Scanned: Yes (on stoneboat.aleph1.co.uk) Subject: Re: [Balloon] Balloon 3 CPU clock scaling and bus timing X-BeenThere: balloon@balloonboard.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: Balloon List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 Sep 2009 08:15:46 -0000 Wookey wrote: > +++ Chris Jones [2009-09-16 22:07 +0100]: >> To sort this out, I've created another kernel patch (balloon3-cpufreq, >> only against 2.6.29.1 at the moment) which adjusts the table of CPU >> clock frequencies in cpufreq-pxa2xx.c so that the memory clock always >> runs at 104MHz. > > Does this mean that we need to have CONFIG_CPU_FREQ=y in order for > samosa to work reliably? The answer is a resounding 'probably'. I don't know what speed the CPU and bus run at if CONFIG_CPU_FREQ isn't set. If the kernel leaves all the clock configuration registers alone, it'll end up running at whatever speed bootldr left it at. At the moment, bootldr leaves the bus running at 104MHz, so Samosa would work reliably, but you can probably see that this is a fragile state of affairs. Chris -- Chris Jones - chris@martin-jones.com Martin-Jones Technology Ltd, makers of Solidlights 148 Catharine Street, Cambridge, CB1 3AR, UK Phone +44 (0) 1223 655611 Fax +44 (0) 870 112 3908 http://www.solidlights.co.uk/