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, 7 insertions, 9 deletions

diff --git a/drivers/cpufreq/unicore2-cpufreq.c b/drivers/cpufreq/unicore2-cpufreq.c
index 653ae2955b55..86f6cfec2e09 100644
--- a/drivers/cpufreq/unicore2-cpufreq.c
+++ b/drivers/cpufreq/unicore2-cpufreq.c
@@ -46,20 +46,18 @@ static int ucv2_target(struct cpufreq_policy *policy,
 			 unsigned int target_freq,
 			 unsigned int relation)
 {
-	unsigned int cur = ucv2_getspeed(0);
 	struct cpufreq_freqs freqs;
 	struct clk *mclk = clk_get(NULL, "MAIN_CLK");
+	int ret;
 
-	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
-
-	if (!clk_set_rate(mclk, 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(mclk, target_freq * 1000);
+	cpufreq_notify_post_transition(policy, &freqs, ret);
 
-	return 0;
+	return ret;
 }
 
 static int __init ucv2_cpu_init(struct cpufreq_policy *policy)