cpufreq: intel_pstate: set stale CPU frequency to minimum

commit d51847acb018d83186e4af67bc93f9a00a8644f7 upstream.

The intel_pstate CPU frequency scaling driver does not
use policy->cur and it is 0.
When the CPU frequency is outdated arch_freq_get_on_cpu()
will default to the nominal clock frequency when its call to
cpufreq_quick_getpolicy_cur returns the never updated 0.
Thus, the listed frequency might be outside of currently
set limits. Some users are complaining about the high
reported frequency, albeit stale, when their system is
idle and/or it is above the reduced maximum they have set.

This patch will maintain policy_cur for the intel_pstate
driver at the current minimum CPU frequency.

Reported-by: Yang Jie <yang.jie@linux.intel.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217597
Signed-off-by: Doug Smythies <dsmythies@telus.net>
[ rjw: White space damage fixes and comment adjustment ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index f29182512b982b1b639052ae0db9c05c490536ce..1d025bf7dc079770ca3103913f0d56745ce46d39 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -2570,6 +2570,11 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
                        intel_pstate_clear_update_util_hook(policy->cpu);
                intel_pstate_hwp_set(policy->cpu);
        }
+       /*
+        * policy->cur is never updated with the intel_pstate driver, but it
+        * is used as a stale frequency value. So, keep it within limits.
+        */
+       policy->cur = policy->min;
 
        mutex_unlock(&intel_pstate_limits_lock);