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Commit ef54d5ad authored by Zhao Yakui's avatar Zhao Yakui Committed by Len Brown
Browse files

ACPI: Enforce T-state limit changes immediately 



When a T-state limit change notification is received,
Linux must evaluate _TPC and change its current
T-state immediately to comply with the new limit.

Previously, Linux would notice the new limit
only upon the next throttling change.

Signed-off-by: default avatarZhao Yakui <yakui.zhao@intel.com>
Signed-off-by: default avatarLi Shaohua <shaohua.li@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 8c086340

drivers/acpi/processor_throttling.c

+49 −1
Original line number Diff line number Diff line
@@ -70,7 +70,55 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr) 


int acpi_processor_tstate_has_changed(struct acpi_processor *pr)

{

	return acpi_processor_get_platform_limit(pr);

	int result = 0;

	int throttling_limit;

	int current_state;

	struct acpi_processor_limit *limit;

	int target_state;



	result = acpi_processor_get_platform_limit(pr);

	if (result) {

		/* Throttling Limit is unsupported */

		return result;

	}



	throttling_limit = pr->throttling_platform_limit;

	if (throttling_limit >= pr->throttling.state_count) {

		/* Uncorrect Throttling Limit */

		return -EINVAL;

	}



	current_state = pr->throttling.state;

	if (current_state > throttling_limit) {

		/*

		 * The current state can meet the requirement of

		 * _TPC limit. But it is reasonable that OSPM changes

		 * t-states from high to low for better performance.

		 * Of course the limit condition of thermal

		 * and user should be considered.

		 */

		limit = &pr->limit;

		target_state = throttling_limit;

		if (limit->thermal.tx > target_state)

			target_state = limit->thermal.tx;

		if (limit->user.tx > target_state)

			target_state = limit->user.tx;

	} else if (current_state == throttling_limit) {

		/*

		 * Unnecessary to change the throttling state

		 */

		return 0;

	} else {

		/*

		 * If the current state is lower than the limit of _TPC, it

		 * will be forced to switch to the throttling state defined

		 * by throttling_platfor_limit.

		 * Because the previous state meets with the limit condition

		 * of thermal and user, it is unnecessary to check it again.

		 */

		target_state = throttling_limit;

	}

	return acpi_processor_set_throttling(pr, target_state);

}



/*