Re: [PATCH V2 4/7] cpufreq: Add a notification message that the highest perf has changed

[Mario Limonciello <mario.limonciello@amd.com>]

On 8/15/2023 01:15, Meng Li wrote:
> Please refer to the ACPI_Spec for details on the highest
> performance and notify events of CPPC.

I would suggest wording this differently. Maybe something like:

ACPI 6.5 section 8.4.6.1.1.1 specifies that Notify event 0x85 can be
emitted to cause the the OSPM to re-evaluate the highest performance
register.  Add support for this event.

> 
> Signed-off-by: Meng Li <li.meng@amd.com>
> Link: https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html?highlight=cppc#cpc-continuous-performance-control
> ---
>   drivers/acpi/processor_driver.c |  6 ++++++
>   drivers/cpufreq/cpufreq.c       | 13 +++++++++++++
>   include/linux/cpufreq.h         |  4 ++++
>   3 files changed, 23 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);
> +		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 50bbc969ffe5..842357abfae6 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2675,6 +2675,19 @@ 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 172ff51c1b2a..766c83a4fae7 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -231,6 +231,7 @@ 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);
> @@ -376,6 +377,9 @@ 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);
>