@@ -38,19 +38,17 @@ static int ucv2_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
- unsigned int cur = policy->cur;
struct cpufreq_freqs freqs;
+ int ret;
- cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
-
- if (!clk_set_rate(policy->clk, target_freq * 1000)) {
- freqs.old = cur;
- freqs.new = target_freq;
- }
+ freqs.old = policy->cur;
+ freqs.new = target_freq;
- cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
+ cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
+ ret = clk_set_rate(policy->clk, target_freq * 1000);
+ cpufreq_notify_post_transition(policy, &freqs, ret);
- return 0;
+ return ret;
}
static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
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. Also it returns a proper error message in case frequency transition failed. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/unicore2-cpufreq.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-)