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authorViresh Kumar <viresh.kumar@linaro.org>2013-12-02 11:04:13 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-01-06 01:43:44 +0100
commitab1b1c4e8223f9ee66aa93aaf64c36e77cadffac (patch)
treeb592025459590a4564fd8e7760707c7d77a159e1 /drivers/cpufreq/powernow-k8.c
parentf7ba3b41e27129575201f0f9656e83fb67e86c3b (diff)
downloadleg-kernel-ab1b1c4e8223f9ee66aa93aaf64c36e77cadffac.tar.gz
cpufreq: send new set of notification for transition failures
In the current code, if we fail during a frequency transition, we simply send the POSTCHANGE notification with the old frequency. This isn't enough. One of the core users of these notifications is the code responsible for keeping loops_per_jiffy aligned with frequency changes. And mostly it is written as: if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { update-loops-per-jiffy... } So, suppose we are changing to a higher frequency and failed during transition, then following will happen: - CPUFREQ_PRECHANGE notification with freq-new > freq-old - CPUFREQ_POSTCHANGE notification with freq-new == freq-old The first one will update loops_per_jiffy and second one will do nothing. Even if we send the 2nd notification by exchanging values of freq-new and old, some users of these notifications might get unstable. This can be fixed by simply calling cpufreq_notify_post_transition() with error code and this routine will take care of sending notifications in the correct order. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> [rjw: Folded 3 patches into one, rebased unicore2 changes] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/powernow-k8.c')
-rw-r--r--drivers/cpufreq/powernow-k8.c7
1 files changed, 1 insertions, 6 deletions
diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 0023c7d40a51..e10b646634d7 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -964,14 +964,9 @@ static int transition_frequency_fidvid(struct powernow_k8_data *data,
cpufreq_cpu_put(policy);
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
-
res = transition_fid_vid(data, fid, vid);
- if (res)
- freqs.new = freqs.old;
- else
- freqs.new = find_khz_freq_from_fid(data->currfid);
+ cpufreq_notify_post_transition(policy, &freqs, res);
- cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
return res;
}