Re: [PATCH V12 4/7] cpufreq: Add a notification message that the highest perf has changed

Rafael J. Wysocki
2023-12-06T20:58:44Z

On Tue, Dec 5, 2023 at 7:38 AM Meng Li <li.meng@amd.com> wrote:
>
> ACPI 6.5 section 8.4.6.1.1.1 specifies that Notify event 0x85 can be
> emmitted to cause the the OSPM to re-evaluate the highest performance

Typos above. Given the number of iterations of this patch, this is
kind of disappointing.

> register. Add support for this event.

Also it would be nice to describe how this is supposed to work at
least roughly, so it is not necessary to reverse-engineer the patch to
find out that.

> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> Reviewed-by: Huang Rui <ray.huang@amd.com>
> Reviewed-by: Perry Yuan <perry.yuan@amd.com>
> Signed-off-by: Meng Li <li.meng@amd.com>
> Link: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#processor-device-notification-values
> ---
> drivers/acpi/processor_driver.c | 6 ++++++
> drivers/cpufreq/cpufreq.c | 13 +++++++++++++
> include/linux/cpufreq.h | 5 +++++
> 3 files changed, 24 insertions(+)
>
> diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
> index 4bd16b3f0781..29b2fb68a35d 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -27,6 +27,7 @@
> #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
> #define ACPI_PROCESSOR_NOTIFY_POWER 0x81
> #define ACPI_PROCESSOR_NOTIFY_THROTTLING 0x82
> +#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED 0x85
>
> MODULE_AUTHOR("Paul Diefenbaugh");
> MODULE_DESCRIPTION("ACPI Processor Driver");
> @@ -83,6 +84,11 @@ static void acpi_processor_notify(acpi_handle handle, u32 event, void *data)
> acpi_bus_generate_netlink_event(device->pnp.device_class,
> dev_name(&device->dev), event, 0);
> break;
> + case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:
> + cpufreq_update_highest_perf(pr->id);

And the design appears to be a bit ad-hoc here.

Because why does it have anything to do with cpufreq?

> + acpi_bus_generate_netlink_event(device->pnp.device_class,
> + dev_name(&device->dev), event, 0);
> + break;
> default:
> acpi_handle_debug(handle, "Unsupported event [0x%x]\n", event);
> break;
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 934d35f570b7..14a4cbc6dd05 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2717,6 +2717,19 @@ void cpufreq_update_limits(unsigned int cpu)
> }
> EXPORT_SYMBOL_GPL(cpufreq_update_limits);
>
> +/**
> + * cpufreq_update_highest_perf - Update highest performance for a given CPU.
> + * @cpu: CPU to update the highest performance for.
> + *
> + * Invoke the driver's ->update_highest_perf callback if present
> + */
> +void cpufreq_update_highest_perf(unsigned int cpu)
> +{
> + if (cpufreq_driver->update_highest_perf)
> + cpufreq_driver->update_highest_perf(cpu);
> +}
> +EXPORT_SYMBOL_GPL(cpufreq_update_highest_perf);
> +
> /*********************************************************************
> * BOOST *
> *********************************************************************/
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 1c5ca92a0555..f62257b2a42f 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -235,6 +235,7 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu);
> void refresh_frequency_limits(struct cpufreq_policy *policy);
> void cpufreq_update_policy(unsigned int cpu);
> void cpufreq_update_limits(unsigned int cpu);
> +void cpufreq_update_highest_perf(unsigned int cpu);
> bool have_governor_per_policy(void);
> bool cpufreq_supports_freq_invariance(void);
> struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy);
> @@ -263,6 +264,7 @@ static inline bool cpufreq_supports_freq_invariance(void)
> return false;
> }
> static inline void disable_cpufreq(void) { }
> +static inline void cpufreq_update_highest_perf(unsigned int cpu) { }
> #endif
>
> #ifdef CONFIG_CPU_FREQ_STAT
> @@ -380,6 +382,9 @@ struct cpufreq_driver {
> /* Called to update policy limits on firmware notifications. */
> void (*update_limits)(unsigned int cpu);
>
> + /* Called to update highest performance on firmware notifications. */
> + void (*update_highest_perf)(unsigned int cpu);
> +
> /* optional */
> int (*bios_limit)(int cpu, unsigned int *limit);
>
> --
> 2.34.1
>
>