cpufreq: conservative: Take limits changes into account properly

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: abb6627910a1 (cpufreq: conservative: Fix next frequency selection)
Fixes: 00bfe05889e9 (cpufreq: conservative: Decrease frequency faster for deferred updates)
Reported-by: Waldemar Rymarkiewicz <waldemarx.rymarkiewicz@intel.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Waldemar Rymarkiewicz <waldemarx.rymarkiewicz@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index f20f20a77d4d37cad47eea9673552478dd1ccf32..4268f87e99fcfb68c60368cfdc13f5033488cfad 100644 (file)
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/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;