From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757028Ab3BFCGh (ORCPT ); Tue, 5 Feb 2013 21:06:37 -0500 Received: from mail-oa0-f54.google.com ([209.85.219.54]:48481 "EHLO mail-oa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754258Ab3BFCGf (ORCPT ); Tue, 5 Feb 2013 21:06:35 -0500 Message-ID: <5111BAA8.5050101@gmail.com> Date: Tue, 05 Feb 2013 18:06:32 -0800 From: Dirk Brandewie User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Viresh Kumar CC: dirk.brandewie@gmail.com, linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org, Dirk Brandewie Subject: Re: [PATCH 3/7] cpufreq: Only query drivers that implement cpufreq_driver.target() References: <1360088646-19104-1-git-send-email-dirk.brandewie@gmail.com> <1360088646-19104-4-git-send-email-dirk.brandewie@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/05/2013 05:47 PM, Viresh Kumar wrote: > On Tue, Feb 5, 2013 at 11:54 PM, wrote: >> From: Dirk Brandewie >> >> Scaling drivers that implement cpufreq_driver.setpolicy() have >> internal governors and may/will change the current operating frequency >> very frequently this will cause cpufreq_out_of_sync() to be called >> every time. Only call cpufreq_driver.get() for drivers that implement >> cpufreq_driver.target() >> >> Signed-off-by: Dirk Brandewie >> --- >> drivers/cpufreq/cpufreq.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >> index 96bc302..d8daa4b 100644 >> --- a/drivers/cpufreq/cpufreq.c >> +++ b/drivers/cpufreq/cpufreq.c >> @@ -1787,7 +1787,7 @@ int cpufreq_update_policy(unsigned int cpu) >> >> /* BIOS might change freq behind our back >> -> ask driver for current freq and notify governors about a change */ >> - if (cpufreq_driver->get) { >> + if (cpufreq_driver->get && cpufreq_driver->target) { >> policy.cur = cpufreq_driver->get(cpu); >> if (!data->cur) { >> pr_debug("Driver did not initialize current freq"); > > I am really not liking copy-pasting my older comments here :( > > "This would mean policy->cur has a garbage value. I don't really know > how would other routine behave on this. Would it make sense to make > policy->cur zero atleast? > " > The driver implements get() and will return a valid value but the other components that track the current frequency will not have been notified about any change so there is nothing to be out of sync with. There is no reason to call cpufreq_out_of_sync() where the driver being used implements an internal governor. --Dirk