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Commit df45db61 authored by Lv Zheng's avatar Lv Zheng Committed by Rafael J. Wysocki
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ACPI / EC: Add PM operations for suspend/resume noirq stage 



It is reported that on some platforms, resume speed is not fast. The cause
is: in noirq stage, EC driver is working in polling mode, and each state
machine advancement requires a context switch.

The context switch is not necessary to the EC driver's polling mode. This
patch implements PM hooks to automatically switch the driver to/from the
busy polling mode to eliminate the overhead caused by the context switch.

This finally contributes to the tuning result: acpi_pm_finish() execution
time is improved from 192ms to 6ms.

Signed-off-by: default avatarLv Zheng <lv.zheng@intel.com>
Reported-and-tested-by: default avatarTodd E Brandt <todd.e.brandt@linux.intel.com>
[ rjw: Subject ]
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 694d0d0b

drivers/acpi/ec.c

+53 −0
Original line number Diff line number Diff line
@@ -1619,6 +1619,58 @@ int __init acpi_ec_ecdt_probe(void) 
	return ret;

}



#ifdef CONFIG_PM_SLEEP

static void acpi_ec_enter_noirq(struct acpi_ec *ec)

{

	unsigned long flags;



	if (ec == first_ec) {

		spin_lock_irqsave(&ec->lock, flags);

		ec->saved_busy_polling = ec_busy_polling;

		ec->saved_polling_guard = ec_polling_guard;

		ec_busy_polling = true;

		ec_polling_guard = 0;

		ec_log_drv("interrupt blocked");

		spin_unlock_irqrestore(&ec->lock, flags);

	}

}



static void acpi_ec_leave_noirq(struct acpi_ec *ec)

{

	unsigned long flags;



	if (ec == first_ec) {

		spin_lock_irqsave(&ec->lock, flags);

		ec_busy_polling = ec->saved_busy_polling;

		ec_polling_guard = ec->saved_polling_guard;

		ec_log_drv("interrupt unblocked");

		spin_unlock_irqrestore(&ec->lock, flags);

	}

}



static int acpi_ec_suspend_noirq(struct device *dev)

{

	struct acpi_ec *ec =

		acpi_driver_data(to_acpi_device(dev));



	acpi_ec_enter_noirq(ec);

	return 0;

}



static int acpi_ec_resume_noirq(struct device *dev)

{

	struct acpi_ec *ec =

		acpi_driver_data(to_acpi_device(dev));



	acpi_ec_leave_noirq(ec);

	return 0;

}

#endif



static const struct dev_pm_ops acpi_ec_pm = {

	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend_noirq, acpi_ec_resume_noirq)

};



static int param_set_event_clearing(const char *val, struct kernel_param *kp)

{

	int result = 0;
@@ -1664,6 +1716,7 @@ static struct acpi_driver acpi_ec_driver = { 
		.add = acpi_ec_add,

		.remove = acpi_ec_remove,

		},

	.drv.pm = &acpi_ec_pm,

};



static inline int acpi_ec_query_init(void)

drivers/acpi/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -174,6 +174,8 @@ struct acpi_ec { 
	struct work_struct work;

	unsigned long timestamp;

	unsigned long nr_pending_queries;

	bool saved_busy_polling;

	unsigned int saved_polling_guard;

};



extern struct acpi_ec *first_ec;