Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752362AbaDYI0n (ORCPT ); Fri, 25 Apr 2014 04:26:43 -0400 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:40783 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752673AbaDYISz (ORCPT ); Fri, 25 Apr 2014 04:18:55 -0400 From: "Srivatsa S. Bhat" Subject: [PATCH 1/3] cpufreq, longhaul: 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: Fri, 25 Apr 2014 13:48:09 +0530 Message-ID: <20140425081804.10258.8324.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140425081728.10258.63980.stgit@srivatsabhat.in.ibm.com> References: <20140425081728.10258.63980.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: 14042508-4790-0000-0000-000001038215 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 longhaul 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 longhaul 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 longhaul driver, since they rightly belong to the cpufreq core. (Note that during module_exit(), the longhaul 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.) Reported-by: Meelis Roos Signed-off-by: Srivatsa S. Bhat --- drivers/cpufreq/longhaul.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/cpufreq/longhaul.c b/drivers/cpufreq/longhaul.c index d00e5d1..9b6dd9a 100644 --- a/drivers/cpufreq/longhaul.c +++ b/drivers/cpufreq/longhaul.c @@ -269,8 +269,6 @@ static void longhaul_setstate(struct cpufreq_policy *policy, freqs.old = calc_speed(longhaul_get_cpu_mult()); freqs.new = speed; - cpufreq_freq_transition_begin(policy, &freqs); - pr_debug("Setting to FSB:%dMHz Mult:%d.%dx (%s)\n", fsb, mult/10, mult%10, print_speed(speed/1000)); retry_loop: @@ -385,8 +383,6 @@ retry_loop: goto retry_loop; } } - /* Report true CPU frequency */ - cpufreq_freq_transition_end(policy, &freqs, 0); if (!bm_timeout) printk(KERN_INFO PFX "Warning: Timeout while waiting for " @@ -968,7 +964,15 @@ static void __exit longhaul_exit(void) for (i = 0; i < numscales; i++) { if (mults[i] == maxmult) { + struct cpufreq_freqs freqs; + + freqs.old = policy->cur; + freqs.new = longhaul_table[i].frequency; + freqs.flags = 0; + + cpufreq_freq_transition_begin(policy, &freqs); longhaul_setstate(policy, i); + cpufreq_freq_transition_end(policy, &freqs, 0); break; } } -- 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/