Commit b9e95fc6 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

ACPI / LPSS: Power up LPSS devices during enumeration 



Commit 7cd8407d (ACPI / PM: Do not execute _PS0 for devices without
_PSC during initialization) introduced a regression on some systems
with Intel Lynxpoint Low-Power Subsystem (LPSS) where some devices
need to be powered up during initialization, but their device objects
in the ACPI namespace have _PS0 and _PS3 only (without _PSC or power
resources).

To work around this problem, make the ACPI LPSS driver power up
devices it knows about by using a new helper function
acpi_device_fix_up_power() that does all of the necessary
sanity checks and calls acpi_dev_pm_explicit_set() to put the
device into D0.

Reported-and-tested-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 6ee22e9d

drivers/acpi/acpi_lpss.c

+15 −6
Original line number Diff line number Diff line
@@ -164,13 +164,22 @@ static int acpi_lpss_create_device(struct acpi_device *adev, 
	if (dev_desc->clk_required) {

		ret = register_device_clock(adev, pdata);

		if (ret) {

			/* Skip the device, but continue the namespace scan. */

			ret = 0;

			goto err_out;

		}

	}



	/*

			 * Skip the device, but don't terminate the namespace

			 * scan.

	 * This works around a known issue in ACPI tables where LPSS devices

	 * have _PS0 and _PS3 without _PSC (and no power resources), so

	 * acpi_bus_init_power() will assume that the BIOS has put them into D0.

	 */

			kfree(pdata);

			return 0;

		}

	ret = acpi_device_fix_up_power(adev);

	if (ret) {

		/* Skip the device, but continue the namespace scan. */

		ret = 0;

		goto err_out;

	}



	adev->driver_data = pdata;

drivers/acpi/device_pm.c

+20 −0
Original line number Diff line number Diff line
@@ -290,6 +290,26 @@ int acpi_bus_init_power(struct acpi_device *device) 
	return 0;

}



/**

 * acpi_device_fix_up_power - Force device with missing _PSC into D0.

 * @device: Device object whose power state is to be fixed up.

 *

 * Devices without power resources and _PSC, but having _PS0 and _PS3 defined,

 * are assumed to be put into D0 by the BIOS.  However, in some cases that may

 * not be the case and this function should be used then.

 */

int acpi_device_fix_up_power(struct acpi_device *device)

{

	int ret = 0;



	if (!device->power.flags.power_resources

	    && !device->power.flags.explicit_get

	    && device->power.state == ACPI_STATE_D0)

		ret = acpi_dev_pm_explicit_set(device, ACPI_STATE_D0);



	return ret;

}



int acpi_bus_update_power(acpi_handle handle, int *state_p)

{

	struct acpi_device *device;

include/acpi/acpi_bus.h

+1 −0
Original line number Diff line number Diff line
@@ -382,6 +382,7 @@ const char *acpi_power_state_string(int state); 
int acpi_device_get_power(struct acpi_device *device, int *state);

int acpi_device_set_power(struct acpi_device *device, int state);

int acpi_bus_init_power(struct acpi_device *device);

int acpi_device_fix_up_power(struct acpi_device *device);

int acpi_bus_update_power(acpi_handle handle, int *state_p);

bool acpi_bus_power_manageable(acpi_handle handle);

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