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author | Viresh Kumar <viresh.kumar@linaro.org> | 2013-12-02 05:34:13 (GMT) |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2014-01-06 00:43:44 (GMT) |
commit | ab1b1c4e8223f9ee66aa93aaf64c36e77cadffac (patch) | |
tree | b592025459590a4564fd8e7760707c7d77a159e1 /drivers/cpufreq/powernow-k8.c | |
parent | f7ba3b41e27129575201f0f9656e83fb67e86c3b (diff) | |
download | linux-ab1b1c4e8223f9ee66aa93aaf64c36e77cadffac.tar.xz |
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.c | 7 |
1 files changed, 1 insertions, 6 deletions
diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c index 0023c7d..e10b646 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; } |