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>

1 files changed, 2 insertions, 11 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a123a731ec4e..d533c205eea4 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1739,17 +1739,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
 			pr_err("%s: Failed to change cpu frequency: %d\n",
 					__func__, retval);
 
-		if (notify) {
-			/*
-			 * Notify with old freq in case we failed to change
-			 * frequency
-			 */
-			if (retval)
-				freqs.new = freqs.old;
-
-			cpufreq_notify_transition(policy, &freqs,
-					CPUFREQ_POSTCHANGE);
-		}
+		if (notify)
+			cpufreq_notify_post_transition(policy, &freqs, retval);
 	}
 
 out: