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Commit d0ea59e1 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpufreq: intel_pstate: Request P-states control from SMM if needed 



Currently, intel_pstate is unable to control P-states on my
IvyBridge-based Acer Aspire S5, because they are controlled by SMM
on that machine by default and it is necessary to request OS control
of P-states from it via the SMI Command register exposed in the ACPI
FADT.  intel_pstate doesn't do that now, but acpi-cpufreq and other
cpufreq drivers for x86 platforms do.

Address this problem by making intel_pstate use the ACPI-defined
mechanism as well.  However, intel_pstate is not modular and it
doesn't need the module refcount tricks played by
acpi_processor_notify_smm(), so export the core of this function
to it as acpi_processor_pstate_control() and make it call that.
[The changes in processor_perflib.c related to this should not
make any functional difference for the acpi_processor_notify_smm()
users].

To be safe, only call acpi_processor_notify_smm() from intel_pstate
if ACPI _PPC support is enabled in it.

Suggested-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
parent f0da898b

drivers/acpi/processor_perflib.c

+28 −17
Original line number Diff line number Diff line
@@ -465,11 +465,33 @@ int acpi_processor_get_performance_info(struct acpi_processor *pr) 
	return result;

}

EXPORT_SYMBOL_GPL(acpi_processor_get_performance_info);

int acpi_processor_notify_smm(struct module *calling_module)



int acpi_processor_pstate_control(void)

{

	acpi_status status;

	static int is_done = 0;



	if (!acpi_gbl_FADT.smi_command || !acpi_gbl_FADT.pstate_control)

		return 0;



	ACPI_DEBUG_PRINT((ACPI_DB_INFO,

			  "Writing pstate_control [0x%x] to smi_command [0x%x]\n",

			  acpi_gbl_FADT.pstate_control, acpi_gbl_FADT.smi_command));



	status = acpi_os_write_port(acpi_gbl_FADT.smi_command,

				    (u32)acpi_gbl_FADT.pstate_control, 8);

	if (ACPI_SUCCESS(status))

		return 1;



	ACPI_EXCEPTION((AE_INFO, status,

			"Failed to write pstate_control [0x%x] to smi_command [0x%x]",

			acpi_gbl_FADT.pstate_control, acpi_gbl_FADT.smi_command));

	return -EIO;

}



int acpi_processor_notify_smm(struct module *calling_module)

{

	static int is_done = 0;

	int result;



	if (!(acpi_processor_ppc_status & PPC_REGISTERED))

		return -EBUSY;
@@ -492,26 +514,15 @@ int acpi_processor_notify_smm(struct module *calling_module) 


	is_done = -EIO;



	/* Can't write pstate_control to smi_command if either value is zero */

	if ((!acpi_gbl_FADT.smi_command) || (!acpi_gbl_FADT.pstate_control)) {

	result = acpi_processor_pstate_control();

	if (!result) {

		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No SMI port or pstate_control\n"));

		module_put(calling_module);

		return 0;

	}



	ACPI_DEBUG_PRINT((ACPI_DB_INFO,

			  "Writing pstate_control [0x%x] to smi_command [0x%x]\n",

			  acpi_gbl_FADT.pstate_control, acpi_gbl_FADT.smi_command));



	status = acpi_os_write_port(acpi_gbl_FADT.smi_command,

				    (u32) acpi_gbl_FADT.pstate_control, 8);

	if (ACPI_FAILURE(status)) {

		ACPI_EXCEPTION((AE_INFO, status,

				"Failed to write pstate_control [0x%x] to "

				"smi_command [0x%x]", acpi_gbl_FADT.pstate_control,

				acpi_gbl_FADT.smi_command));

	if (result < 0) {

		module_put(calling_module);

		return status;

		return result;

	}



	/* Success. If there's no _PPC, we need to fear nothing, so

drivers/cpufreq/intel_pstate.c

+13 −0
Original line number Diff line number Diff line
@@ -1909,9 +1909,20 @@ static bool __init intel_pstate_platform_pwr_mgmt_exists(void) 


	return false;

}



static void intel_pstate_request_control_from_smm(void)

{

	/*

	 * It may be unsafe to request P-states control from SMM if _PPC support

	 * has not been enabled.

	 */

	if (acpi_ppc)

		acpi_processor_pstate_control();

}

#else /* CONFIG_ACPI not enabled */

static inline bool intel_pstate_platform_pwr_mgmt_exists(void) { return false; }

static inline bool intel_pstate_has_acpi_ppc(void) { return false; }

static inline void intel_pstate_request_control_from_smm(void) {}

#endif /* CONFIG_ACPI */



static const struct x86_cpu_id hwp_support_ids[] __initconst = {
@@ -1963,6 +1974,8 @@ static int __init intel_pstate_init(void) 
	if (!hwp_active && hwp_only)

		goto out;



	intel_pstate_request_control_from_smm();



	rc = cpufreq_register_driver(&intel_pstate_driver);

	if (rc)

		goto out;

include/acpi/processor.h

+1 −0
Original line number Diff line number Diff line
@@ -249,6 +249,7 @@ extern int acpi_processor_register_performance(struct acpi_processor_performance 
					       *performance, unsigned int cpu);

extern void acpi_processor_unregister_performance(unsigned int cpu);



int acpi_processor_pstate_control(void);

/* note: this locks both the calling module and the processor module

         if a _PPC object exists, rmmod is disallowed then */

int acpi_processor_notify_smm(struct module *calling_module);