linux-kernel - [PATCH v1 2/2] cpufreq: intel_pstate: Update asym capacity for CPUs that were offline initially

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Message-ID: <1913414.tdWV9SEqCh@rjwysocki.net>
Date: Mon, 04 Nov 2024 19:53:53 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Subject:
 [PATCH v1 2/2] cpufreq: intel_pstate: Update asym capacity for CPUs that were
 offline initially

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

Commit 929ebc93ccaa ("cpufreq: intel_pstate: Set asymmetric CPU
capacity on hybrid systems") overlooked a corner case in which some
CPUs may be offline to start with and brought back online later,
after the intel_pstate driver has been registered, so their asymmetric
capacity will not be set.

Address this by calling hybrid_update_capacity() in the CPU
initialization path that is executed instead of the online path
for those CPUs.

Note that this asymmetric capacity update will be skipped during
driver initialization and mode switches because hybrid_max_perf_cpu
is NULL in those cases.

Fixes: 929ebc93ccaa ("cpufreq: intel_pstate: Set asymmetric CPU capacity on hybrid systems")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/intel_pstate.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -2275,6 +2275,11 @@ static void intel_pstate_get_cpu_pstates
 		} else {
 			cpu->pstate.scaling = perf_ctl_scaling;
 		}
+		/*
+		 * If the CPU is going online for the first time and it was
+		 * offline initially, asym capacity scaling needs to be updated.
+		 */
+		hybrid_update_capacity(cpu);
 	} else {
 		cpu->pstate.scaling = perf_ctl_scaling;
 		cpu->pstate.max_pstate = pstate_funcs.get_max(cpu->cpu);