Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932854AbaD1T0F (ORCPT ); Mon, 28 Apr 2014 15:26:05 -0400 Received: from e23smtp02.au.ibm.com ([202.81.31.144]:35902 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932670AbaD1T0A (ORCPT ); Mon, 28 Apr 2014 15:26:00 -0400 From: "Srivatsa S. Bhat" Subject: [PATCH v2 3/5] cpufreq, powernow-k6: Fix double invocation of cpufreq_freq_transition_begin/end To: rjw@rjwysocki.net, mroos@linux.ee, viresh.kumar@linaro.org Cc: cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com Date: Tue, 29 Apr 2014 00:24:42 +0530 Message-ID: <20140428185434.28755.49098.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140428185331.28755.899.stgit@srivatsabhat.in.ibm.com> References: <20140428185331.28755.899.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14042818-5490-0000-0000-0000058578A7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During frequency transitions, the cpufreq core takes the responsibility of invoking cpufreq_freq_transition_begin() and cpufreq_freq_transition_end() for those cpufreq drivers that define the ->target_index callback but don't set the ASYNC_NOTIFICATION flag. The powernow-k6 cpufreq driver falls under this category, but this driver was invoking the _begin() and _end() APIs itself around frequency transitions, which led to double invocation of the _begin() API. The _begin API makes contending callers wait until the previous invocation is complete. Hence, the powernow-k6 driver ended up waiting on itself, leading to system hangs during boot. Fix this by removing the calls to the _begin() and _end() APIs from the powernow-k6 driver, since they rightly belong to the cpufreq core. (Note that during ->exit(), the powernow-k6 driver sets the frequency without any help from the cpufreq core. So add explicit calls to the _begin() and _end() APIs around that frequency transition alone, to take care of that special case. Also, add a missing 'break' statement there.) Signed-off-by: Srivatsa S. Bhat Acked-by: Viresh Kumar --- drivers/cpufreq/powernow-k6.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/drivers/cpufreq/powernow-k6.c b/drivers/cpufreq/powernow-k6.c index 695a68c..78904e6 100644 --- a/drivers/cpufreq/powernow-k6.c +++ b/drivers/cpufreq/powernow-k6.c @@ -138,22 +138,14 @@ static void powernow_k6_set_cpu_multiplier(unsigned int best_i) static int powernow_k6_target(struct cpufreq_policy *policy, unsigned int best_i) { - struct cpufreq_freqs freqs; if (clock_ratio[best_i].driver_data > max_multiplier) { printk(KERN_ERR PFX "invalid target frequency\n"); return -EINVAL; } - freqs.old = busfreq * powernow_k6_get_cpu_multiplier(); - freqs.new = busfreq * clock_ratio[best_i].driver_data; - - cpufreq_freq_transition_begin(policy, &freqs); - powernow_k6_set_cpu_multiplier(best_i); - cpufreq_freq_transition_end(policy, &freqs, 0); - return 0; } @@ -229,8 +221,18 @@ static int powernow_k6_cpu_exit(struct cpufreq_policy *policy) unsigned int i; for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) { - if (clock_ratio[i].driver_data == max_multiplier) + if (clock_ratio[i].driver_data == max_multiplier) { + struct cpufreq_freqs freqs; + + freqs.old = policy->cur; + freqs.new = clock_ratio[i].frequency; + freqs.flags = 0; + + cpufreq_freq_transition_begin(policy, &freqs); powernow_k6_target(policy, i); + cpufreq_freq_transition_end(policy, &freqs, 0); + break; + } } return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/