cpufreq: conservative: Take limits changes into account properly

commit da5e79b upstream.

If the policy limits change between invocations of cs_dbs_update(),
the requested frequency value stored in dbs_info may not be updated
and the function may use a stale value of it next time.  Moreover, if
idle periods are takem into account by cs_dbs_update(), the requested
frequency value stored in dbs_info may be below the min policy limit,
which is incorrect.

To fix these problems, always update the requested frequency value
in dbs_info along with the local copy of it when the previous
requested frequency is beyond the policy limits and avoid decreasing
the requested frequency below the min policy limit when taking
idle periods into account.

Fixes: abb6627 (cpufreq: conservative: Fix next frequency selection)
Fixes: 00bfe05 (cpufreq: conservative: Decrease frequency faster for deferred updates)
Reported-by: Waldemar Rymarkiewicz <[email protected]>
Cc: All applicable <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Waldemar Rymarkiewicz <[email protected]>
Acked-by: Viresh Kumar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: rafaeljw

drivers/cpufreq/cpufreq_conservative.c

@@ -80,8 +80,10 @@ static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
 	 * changed in the meantime, so fall back to current frequency in that
 	 * case.
 	 */
-	if (requested_freq > policy->max || requested_freq < policy->min)
+	if (requested_freq > policy->max || requested_freq < policy->min) {
 		requested_freq = policy->cur;
+		dbs_info->requested_freq = requested_freq;
+	}
 
 	freq_step = get_freq_step(cs_tuners, policy);
 
@@ -92,7 +94,7 @@ static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
 	if (policy_dbs->idle_periods < UINT_MAX) {
 		unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
 
-		if (requested_freq > freq_steps)
+		if (requested_freq > policy->min + freq_steps)
 			requested_freq -= freq_steps;
 		else
 			requested_freq = policy->min;