From: Rafael J. Wysocki rafael.j.wysocki@intel.com
commit e0be38ed4ab413ddd492118cf146369b86ee0ab5 upstream.
If the cpufreq policy max limit is changed when intel_pstate operates in the passive mode with HWP enabled and the "powersave" governor is used on top of it, the HWP max limit is not updated as appropriate.
Namely, in the "powersave" governor case, the target P-state is always equal to the policy min limit, so if the latter does not change, intel_cpufreq_adjust_hwp() is not invoked to update the HWP Request MSR due to the "target_pstate != old_pstate" check in intel_cpufreq_update_pstate(), so the HWP max limit is not updated as a result.
Also, if the CPUFREQ_NEED_UPDATE_LIMITS flag is not set for the driver and the target frequency does not change along with the policy max limit, the "target_freq == policy->cur" check in __cpufreq_driver_target() prevents the driver's ->target() callback from being invoked at all, so the HWP max limit is not updated.
To prevent that occurring, set the CPUFREQ_NEED_UPDATE_LIMITS flag in the intel_cpufreq driver structure if HWP is enabled and modify intel_cpufreq_update_pstate() to do the "target_pstate != old_pstate" check only in the non-HWP case and let intel_cpufreq_adjust_hwp() always run in the HWP case (it will update HWP Request only if the cached value of the register is different from the new one including the limits, so if neither the target P-state value nor the max limit changes, the register write will still be avoided).
Fixes: f6ebbcf08f37 ("cpufreq: intel_pstate: Implement passive mode with HWP enabled") Reported-by: Zhang Rui rui.zhang@intel.com Cc: 5.9+ stable@vger.kernel.org # 5.9+: 1c534352f47f cpufreq: Introduce CPUFREQ_NEED_UPDATE_LIMITS ... Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Acked-by: Viresh Kumar viresh.kumar@linaro.org Tested-by: Zhang Rui rui.zhang@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/cpufreq/intel_pstate.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
--- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -2550,14 +2550,12 @@ static int intel_cpufreq_update_pstate(s int old_pstate = cpu->pstate.current_pstate;
target_pstate = intel_pstate_prepare_request(cpu, target_pstate); - if (target_pstate != old_pstate) { + if (hwp_active) { + intel_cpufreq_adjust_hwp(cpu, target_pstate, fast_switch); + cpu->pstate.current_pstate = target_pstate; + } else if (target_pstate != old_pstate) { + intel_cpufreq_adjust_perf_ctl(cpu, target_pstate, fast_switch); cpu->pstate.current_pstate = target_pstate; - if (hwp_active) - intel_cpufreq_adjust_hwp(cpu, target_pstate, - fast_switch); - else - intel_cpufreq_adjust_perf_ctl(cpu, target_pstate, - fast_switch); }
intel_cpufreq_trace(cpu, fast_switch ? INTEL_PSTATE_TRACE_FAST_SWITCH : @@ -3014,6 +3012,7 @@ static int __init intel_pstate_init(void hwp_mode_bdw = id->driver_data; intel_pstate.attr = hwp_cpufreq_attrs; intel_cpufreq.attr = hwp_cpufreq_attrs; + intel_cpufreq.flags |= CPUFREQ_NEED_UPDATE_LIMITS; if (!default_driver) default_driver = &intel_pstate;