From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: [PATCH v2 0/5] Cpufreq frequency serialization fixes Date: Tue, 29 Apr 2014 00:23:54 +0530 Message-ID: <20140428185331.28755.899.stgit@srivatsabhat.in.ibm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" 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 Hi, Meelis Roos reported hangs during boot in the longhaul cpufreq driver, after commit 12478cf0c55 (cpufreq: Make sure frequency transitions are serialized). The root-cause of this issue is the extra invocation of the cpufreq_freq_transition_begin() and cpufreq_freq_transition_end() APIs in the longhaul driver. I found similar issues in the powernow-k6 and powernow-k7 drivers as well. This patchset fixes the issue in all the 3 drivers and also adds a debug infrastructure to catch such issues easily. Patches 1-4 fix the regression in longhaul, powernow-k6 and powernow-k7 drivers. (Patch 2 fixes a different bug in powernow-k6, and it is kept as a separate patch instead of merging it with patch 3, because I felt that it was a bit subtle and needed attention in a separate patch). Patch 5 adds a debug infrastructure to the cpufreq core to catch such problems more easily in the future. Changes in v2: -------------- * Modified patch 1 to take error returns into account, as pointed out by Viresh. * Added patch 2 to fix the existing issue in the powernow-k6 driver, pointed out by Viresh. * Added patch 5 to introduce a debug infrastructure to catch such issues easily. Srivatsa S. Bhat (5): cpufreq, longhaul: Fix double invocation of cpufreq_freq_transition_begin/end cpufreq, powernow-k6: Fix incorrect comparison with max_multipler cpufreq, powernow-k6: Fix double invocation of cpufreq_freq_transition_begin/end cpufreq, powernow-k7: Fix double invocation of cpufreq_freq_transition_begin/end cpufreq: Catch double invocations of cpufreq_freq_transition_begin/end drivers/cpufreq/cpufreq.c | 12 ++++++++++++ drivers/cpufreq/longhaul.c | 36 ++++++++++++++++++++++++------------ drivers/cpufreq/powernow-k6.c | 23 +++++++++++++---------- drivers/cpufreq/powernow-k7.c | 4 ---- include/linux/cpufreq.h | 1 + 5 files changed, 50 insertions(+), 26 deletions(-) Thanks, Srivatsa S. Bhat IBM Linux Technology Center