From: Rafael J. Wysocki rafael.j.wysocki@intel.com
commit d1e7c2996e988866e7ceceb4641a0886885b7889 upstream.
Because sugov_update_next_freq() may skip a frequency update even if the need_freq_update flag has been set for the policy at hand, policy limits updates may not take effect as expected.
For example, if the intel_pstate driver operates in the passive mode with HWP enabled, it needs to update the HWP min and max limits when the policy min and max limits change, respectively, but that may not happen if the target frequency does not change along with the limit at hand. In particular, if the policy min is changed first, causing the target frequency to be adjusted to it, and the policy max limit is changed later to the same value, the HWP max limit will not be updated to follow it as expected, because the target frequency is still equal to the policy min limit and it will not change until that limit is updated.
To address this issue, modify get_next_freq() to let the driver callback run if the CPUFREQ_NEED_UPDATE_LIMITS cpufreq driver flag is set regardless of whether or not the new frequency to set is equal to the previous one.
Fixes: f6ebbcf08f37 ("cpufreq: intel_pstate: Implement passive mode with HWP enabled") Reported-by: Zhang Rui rui.zhang@intel.com Tested-by: Zhang Rui rui.zhang@intel.com Cc: 5.9+ stable@vger.kernel.org # 5.9+: 1c534352f47f cpufreq: Introduce CPUFREQ_NEED_UPDATE_LIMITS ... Cc: 5.9+ stable@vger.kernel.org # 5.9+: a62f68f5ca53 cpufreq: Introduce cpufreq_driver_test_flags() Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Acked-by: Viresh Kumar viresh.kumar@linaro.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/sched/cpufreq_schedutil.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -102,7 +102,8 @@ static bool sugov_should_update_freq(str static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time, unsigned int next_freq) { - if (sg_policy->next_freq == next_freq) + if (sg_policy->next_freq == next_freq && + !cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS)) return false;
sg_policy->next_freq = next_freq; @@ -175,7 +176,8 @@ static unsigned int get_next_freq(struct
freq = map_util_freq(util, freq, max);
- if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update) + if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update && + !cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS)) return sg_policy->next_freq;
sg_policy->need_freq_update = false;