| Message ID | 9c7de55fb06015c1b77e7dafd564b659838864e0.1745511526.git.viresh.kumar@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [V2,1/5] cpufreq: acpi: Re-sync CPU boost state on system resume | expand |
On Thu, Apr 24, 2025 at 6:20 PM Viresh Kumar <viresh.kumar@linaro.org> wrote: > > During CPU hotunplug events (such as those occurring during > suspend/resume cycles), platform firmware may modify the CPU boost > state. > > If boost was disabled prior to CPU removal, it correctly remains > disabled upon re-plug. However, if firmware re-enables boost while the > CPU is offline, the CPU may return with boost enabled—even if it was > originally disabled—once it is hotplugged back in. This leads to > inconsistent behavior and violates user or kernel policy expectations. > > To maintain consistency, ensure the boost state is re-synchronized with > the kernel policy when a CPU is hotplugged back in. > > Note: This re-synchronization is not necessary during the initial call > to ->init() for a CPU, as the cpufreq core handles it via > cpufreq_online(). At that point, acpi_cpufreq_driver.boost_enabled is > initialized to the value returned by boost_state(0). > > Fixes: 2b16c631832d ("cpufreq: ACPI: Remove set_boost in acpi_cpufreq_cpu_init()") > Reported-by: Nicholas Chin <nic.c3.14@gmail.com> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220013 > Tested-by: Nicholas Chin <nic.c3.14@gmail.com> > Reviewed-by: Lifeng Zheng <zhenglifeng1@huawei.com> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> I gather that this patch is for 6.15 and the rest of the series is for 6.16, so applied accordingly. > --- > drivers/cpufreq/acpi-cpufreq.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c > index 924314cdeebc..d26b610e4f24 100644 > --- a/drivers/cpufreq/acpi-cpufreq.c > +++ b/drivers/cpufreq/acpi-cpufreq.c > @@ -909,8 +909,19 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy) > if (perf->states[0].core_frequency * 1000 != freq_table[0].frequency) > pr_warn(FW_WARN "P-state 0 is not max freq\n"); > > - if (acpi_cpufreq_driver.set_boost) > - policy->boost_supported = true; > + if (acpi_cpufreq_driver.set_boost) { > + if (policy->boost_supported) { > + /* > + * The firmware may have altered boost state while the > + * CPU was offline (for example during a suspend-resume > + * cycle). > + */ > + if (policy->boost_enabled != boost_state(cpu)) > + set_boost(policy, policy->boost_enabled); > + } else { > + policy->boost_supported = true; > + } > + } > > return result; > > -- > 2.31.1.272.g89b43f80a514 >
diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c index 924314cdeebc..d26b610e4f24 100644 --- a/drivers/cpufreq/acpi-cpufreq.c +++ b/drivers/cpufreq/acpi-cpufreq.c @@ -909,8 +909,19 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy) if (perf->states[0].core_frequency * 1000 != freq_table[0].frequency) pr_warn(FW_WARN "P-state 0 is not max freq\n"); - if (acpi_cpufreq_driver.set_boost) - policy->boost_supported = true; + if (acpi_cpufreq_driver.set_boost) { + if (policy->boost_supported) { + /* + * The firmware may have altered boost state while the + * CPU was offline (for example during a suspend-resume + * cycle). + */ + if (policy->boost_enabled != boost_state(cpu)) + set_boost(policy, policy->boost_enabled); + } else { + policy->boost_supported = true; + } + } return result;
During CPU hotunplug events (such as those occurring during suspend/resume cycles), platform firmware may modify the CPU boost state. If boost was disabled prior to CPU removal, it correctly remains disabled upon re-plug. However, if firmware re-enables boost while the CPU is offline, the CPU may return with boost enabled—even if it was originally disabled—once it is hotplugged back in. This leads to inconsistent behavior and violates user or kernel policy expectations. To maintain consistency, ensure the boost state is re-synchronized with the kernel policy when a CPU is hotplugged back in. Note: This re-synchronization is not necessary during the initial call to ->init() for a CPU, as the cpufreq core handles it via cpufreq_online(). At that point, acpi_cpufreq_driver.boost_enabled is initialized to the value returned by boost_state(0). Fixes: 2b16c631832d ("cpufreq: ACPI: Remove set_boost in acpi_cpufreq_cpu_init()") Reported-by: Nicholas Chin <nic.c3.14@gmail.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220013 Tested-by: Nicholas Chin <nic.c3.14@gmail.com> Reviewed-by: Lifeng Zheng <zhenglifeng1@huawei.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/acpi-cpufreq.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)