| From e0be38ed4ab413ddd492118cf146369b86ee0ab5 Mon Sep 17 00:00:00 2001 |
| From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> |
| Date: Fri, 23 Oct 2020 17:35:32 +0200 |
| Subject: cpufreq: intel_pstate: Avoid missing HWP max updates in passive mode |
| |
| 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; |
| |