cpufreq: intel_pstate: set stale CPU frequency to minimum

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When the CPU frequency is outdated arch_freq_get_on_cpu()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>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 8ca2bce4341a4091d34afa2d3eb44dcecf59691b..dc50c9fb488dfcc0c5b79c76d57f48bca515e06c 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -2609,6 +2609,11 @@ 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);