[PATCH v1] cpufreq: intel_pstate: Set non-turbo capacity to HWP_GUARANTEED_PERF()

[PATCH v1] cpufreq: intel_pstate: Set non-turbo capacity to HWP_GUARANTEED_PERF()

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Setting cpu->capacity_perf to cpu->pstate.max_pstate_physical in the
"no turbo" case is inconsistent with what happens elsewhere in the
driver and causes arch_scale_cpu_capacity() to be incorrect.  It also
skews arch_scale_freq_capacity() which ends up differing from 1024 for
the guaranteed P-state.

Address that by setting capacity_perf to HWP_GUARANTEED_PERF() in the
"no turbo" case.

Fixes: 929ebc93ccaa ("cpufreq: intel_pstate: Set asymmetric CPU capacity on hybrid systems")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: All applicable <stable@vger.kernel.org>
---
 drivers/cpufreq/intel_pstate.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1007,12 +1007,14 @@ static void hybrid_clear_cpu_capacity(un
 
 static void hybrid_get_capacity_perf(struct cpudata *cpu)
 {
+	u64 hwp_cap = READ_ONCE(cpu->hwp_cap_cached);
+
 	if (READ_ONCE(global.no_turbo)) {
-		cpu->capacity_perf = cpu->pstate.max_pstate_physical;
+		cpu->capacity_perf = HWP_GUARANTEED_PERF(hwp_cap);
 		return;
 	}
 
-	cpu->capacity_perf = HWP_HIGHEST_PERF(READ_ONCE(cpu->hwp_cap_cached));
+	cpu->capacity_perf = HWP_HIGHEST_PERF(hwp_cap);
 }
 
 static void hybrid_set_capacity_of_cpus(void)

Re: [PATCH v1] cpufreq: intel_pstate: Set non-turbo capacity to HWP_GUARANTEED_PERF()

[Ricardo Neri]

On Tue, Jul 07, 2026 at 07:19:55PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Setting cpu->capacity_perf to cpu->pstate.max_pstate_physical in the
> "no turbo" case is inconsistent with what happens elsewhere in the
> driver and causes arch_scale_cpu_capacity() to be incorrect.  It also
> skews arch_scale_freq_capacity() which ends up differing from 1024 for
> the guaranteed P-state.
> 
> Address that by setting capacity_perf to HWP_GUARANTEED_PERF() in the
> "no turbo" case.

Indeed, using cpu->pstate.max_pstate_physical does not make sense. It only
reflects what PLATFORM_INFO[15:8] says for _all_ CPUs, regardless of type,
resized by cpu->pstate.scaling/cpu->pstate.perf_ctl_scaling. No relation
to any property of the CPU.

Now arch_scale_freq_capacity() looks correct.

> 
> Fixes: 929ebc93ccaa ("cpufreq: intel_pstate: Set asymmetric CPU capacity on hybrid systems")
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Tested-by Ricardo Neri <ricardo.neri-calderon@linux.intel.com>