From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Jones Subject: Re: writing a cpufreq driver Date: Thu, 21 Sep 2006 15:47:14 -0400 Message-ID: <20060921194714.GH17065@redhat.com> References: <20060921193141.GE17065@redhat.com> <1449F58C868D8D4E9C72945771150BDF153669@SAUSEXMB1.amd.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <1449F58C868D8D4E9C72945771150BDF153669@SAUSEXMB1.amd.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cpufreq-bounces@lists.linux.org.uk Errors-To: cpufreq-bounces+glkc-cpufreq=m.gmane.org+glkc-cpufreq=m.gmane.org@lists.linux.org.uk Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Langsdorf, Mark" Cc: Cpufreq@lists.linux.org.uk, nemesis@icequake.net On Thu, Sep 21, 2006 at 02:38:22PM -0500, Langsdorf, Mark wrote: > > > 1. The first time cpufreq changes speed, I get the whole > > "Losing some > > > ticks... checking if CPU frequency changed." then > > eventually "Losing too > > > many ticks!" and timer switches to PIT. This does not > > happen when I use > > > the /dev/toshiba driver to change speeds from userspace. > > Not sure what > > > is going on here... SMI handler latency is between 6 and 7 ms. > > > > Is loops_per_jiffy being correctly scaled on a speed transition? > > Hmm, powernow-k7.c seems to be the only driver that's calling > > recalibrate_cpu_khz() > > Do drivers need to be doing that? I would have thought the > time could would do it after receiving the notification. Looking at it again.. cpufreq_notify_transition() is calling adjust_jiffies() which should be doing the same thing, so we should be good to go. It looks like feasible that recalibrate_cpu_khz() could actually be killed off. Dave