| Message ID | be988d856aeb8b612c7e9f0176acfdff35788d74.1385962178.git.viresh.kumar@linaro.org |
|---|---|
| State | New |
| Headers | show |
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; }
In the current code, if we fail during a frequency transition we simply send the POSTCHANGE notification with old frequency. This isn't enough. One of the core user of these notifications is the code responsible for keeping loops_per_jiffy aligned with frequency change. 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 correct order. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/powernow-k8.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)