Re: [PATCH v4 1/5] ACPI / processor_idle: introduce ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Tuesday, April 19, 2016 01:30:09 PM Sudeep Holla wrote:
> ACPI 6.0 adds a new method to specify the CPU idle states(C-states)
> called Low Power Idle(LPI) states. Since new architectures like ARM64
> use only LPIs, introduce ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE to
> encapsulate all the code supporting the old style C-states(_CST)
> 
> This patch will help to extend the processor_idle module to support
> LPI.
> 
> Cc: x86@kernel.org
> Cc: linux-ia64@vger.kernel.org
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  arch/ia64/Kconfig             |  1 +
>  arch/x86/Kconfig              |  1 +
>  drivers/acpi/Kconfig          |  3 ++
>  drivers/acpi/processor_idle.c | 74 +++++++++++++++++++++++++++++--------------
>  include/acpi/processor.h      |  3 +-
>  5 files changed, 57 insertions(+), 25 deletions(-)
> 
> diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
> index b534ebab36ea..717de2a146e2 100644
> --- a/arch/ia64/Kconfig
> +++ b/arch/ia64/Kconfig
> @@ -16,6 +16,7 @@ config IA64
>  	select PCI if (!IA64_HP_SIM)
>  	select ACPI if (!IA64_HP_SIM)
>  	select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
> +	select ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE if ACPI
>  	select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
>  	select HAVE_UNSTABLE_SCHED_CLOCK
>  	select HAVE_IDE
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 2dc18605831f..eb03fd0d63b9 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -37,6 +37,7 @@ config X86
>  	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
>  	select ARCH_MIGHT_HAVE_PC_PARPORT
>  	select ARCH_MIGHT_HAVE_PC_SERIO
> +	select ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE if ACPI
>  	select ARCH_SUPPORTS_ATOMIC_RMW
>  	select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
>  	select ARCH_SUPPORTS_INT128		if X86_64
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 82b96ee8624c..ec289078667c 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -48,6 +48,9 @@ config ACPI_LEGACY_TABLES_LOOKUP
>  config ARCH_MIGHT_HAVE_ACPI_PDC
>  	bool
>  
> +config ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE
> +	bool

It might be better to do

config ACPI_PROCESSOR_CST
	bool
	depends on ia64 || x86

Should it depend on ARCH_HAS_POWER_INIT too?


> +
>  config ACPI_GENERIC_GSI
>  	bool
>  
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 444e3745c8b3..1f3fe54194b5 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -59,6 +59,12 @@ module_param(latency_factor, uint, 0644);
>  
>  static DEFINE_PER_CPU(struct cpuidle_device *, acpi_cpuidle_device);
>  
> +struct cpuidle_driver acpi_idle_driver = {
> +	.name =		"acpi_idle",
> +	.owner =	THIS_MODULE,
> +};
> +
> +#ifdef CONFIG_ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE
>  static
>  DEFINE_PER_CPU(struct acpi_processor_cx * [CPUIDLE_STATE_MAX], acpi_cstate);
>  
> @@ -804,11 +810,6 @@ static void acpi_idle_enter_freeze(struct cpuidle_device *dev,
>  	acpi_idle_do_entry(cx);
>  }
>  
> -struct cpuidle_driver acpi_idle_driver = {
> -	.name =		"acpi_idle",
> -	.owner =	THIS_MODULE,
> -};
> -
>  /**
>   * acpi_processor_setup_cpuidle_cx - prepares and configures CPUIDLE
>   * device i.e. per-cpu data
> @@ -925,6 +926,49 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
>  	return 0;
>  }
>  
> +static inline void acpi_processor_cstate_first_run_checks(void)
> +{
> +	static int first_run;
> +
> +	if (first_run)
> +		return;
> +	dmi_check_system(processor_power_dmi_table);
> +	max_cstate = acpi_processor_cstate_check(max_cstate);
> +	if (max_cstate < ACPI_C_STATES_MAX)
> +		pr_notice("ACPI: processor limited to max C-state %d\n",
> +			  max_cstate);
> +	first_run++;
> +
> +	if (acpi_gbl_FADT.cst_control && !nocst) {
> +		status = acpi_os_write_port(acpi_gbl_FADT.smi_command,
> +					    acpi_gbl_FADT.cst_control, 8);
> +		if (ACPI_FAILURE(status))
> +			ACPI_EXCEPTION((AE_INFO, status,
> +					"Notifying BIOS of _CST ability failed"));
> +	}
> +}
> +#else
> +
> +static inline int disabled_by_idle_boot_param(void) { return 0; }
> +static inline void acpi_processor_cstate_first_run_checks(void) { }
> +static int acpi_processor_get_power_info(struct acpi_processor *pr)
> +{
> +	return -ENODEV;
> +}
> +
> +static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
> +					   struct cpuidle_device *dev)
> +{
> +	return -EINVAL;
> +}
> +
> +static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
> +{
> +	return -EINVAL;
> +}
> +
> +#endif

Add a comment indicating what #ifdef block ends here?

> +
>  int acpi_processor_hotplug(struct acpi_processor *pr)
>  {
>  	int ret = 0;
> @@ -1018,29 +1062,11 @@ int acpi_processor_power_init(struct acpi_processor *pr)
>  	acpi_status status;
>  	int retval;
>  	struct cpuidle_device *dev;
> -	static int first_run;
>  
>  	if (disabled_by_idle_boot_param())
>  		return 0;
>  
> -	if (!first_run) {
> -		dmi_check_system(processor_power_dmi_table);
> -		max_cstate = acpi_processor_cstate_check(max_cstate);
> -		if (max_cstate < ACPI_C_STATES_MAX)
> -			printk(KERN_NOTICE
> -			       "ACPI: processor limited to max C-state %d\n",
> -			       max_cstate);
> -		first_run++;
> -	}
> -
> -	if (acpi_gbl_FADT.cst_control && !nocst) {
> -		status =
> -		    acpi_os_write_port(acpi_gbl_FADT.smi_command, acpi_gbl_FADT.cst_control, 8);
> -		if (ACPI_FAILURE(status)) {
> -			ACPI_EXCEPTION((AE_INFO, status,
> -					"Notifying BIOS of _CST ability failed"));
> -		}
> -	}
> +	acpi_processor_cstate_first_run_checks();
>  
>  	acpi_processor_get_power_info(pr);
>  	pr->flags.power_setup_done = 1;
> diff --git a/include/acpi/processor.h b/include/acpi/processor.h
> index 6f1805dd5d3c..50f2423d31fa 100644
> --- a/include/acpi/processor.h
> +++ b/include/acpi/processor.h
> @@ -242,7 +242,8 @@ extern int acpi_processor_get_performance_info(struct acpi_processor *pr);
>  DECLARE_PER_CPU(struct acpi_processor *, processors);
>  extern struct acpi_processor_errata errata;
>  
> -#ifdef ARCH_HAS_POWER_INIT
> +#if defined(ARCH_HAS_POWER_INIT) && \
> +	defined(CONFIG_ARCH_SUPPORTS_ACPI_PROCESSOR_CSTATE)
>  void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
>  					unsigned int cpu);
>  int acpi_processor_ffh_cstate_probe(unsigned int cpu,
>