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Commit bdf43bbf authored by Bjorn Helgaas's avatar Bjorn Helgaas Committed by Len Brown
Browse files

ACPI: don't check power state after _ON/_OFF 

We used to evaluate _STA to check the power state of a device after
running _ON or _OFF.  But as far as I can tell, there's no benefit
to evaluating _STA, and sometimes we trip over bugs when BIOSes don't
implement _STA correctly.

Yakui says Windows XP doesn't evaluate _STA during power transition.
So let's skip it in Linux, too.  It's conceivable that we'll need to
check _STA in the future for some reason, but until we do, I don't
see a reason to clutter this code path.

References:
    http://bugzilla.kernel.org/show_bug.cgi?id=13243
    http://marc.info/?l=linux-acpi&m=124166053803753&w=2
    http://marc.info/?l=linux-acpi&m=124175761408256&w=2
    http://marc.info/?l=linux-acpi&m=124210593114061&w=2



Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
Acked-by: default avatarMatthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent cd86a536

drivers/acpi/power.c

+2 −26
Original line number Diff line number Diff line
@@ -194,7 +194,7 @@ static int acpi_power_get_list_state(struct acpi_handle_list *list, int *state) 


static int acpi_power_on(acpi_handle handle, struct acpi_device *dev)

{

	int result = 0, state;

	int result = 0;

	int found = 0;

	acpi_status status = AE_OK;

	struct acpi_power_resource *resource = NULL;
@@ -236,18 +236,6 @@ static int acpi_power_on(acpi_handle handle, struct acpi_device *dev) 
	if (ACPI_FAILURE(status))

		return -ENODEV;



	if (!acpi_power_nocheck) {

		/*

		 * If acpi_power_nocheck is set, it is unnecessary to check

		 * the power state after power transition.

		 */

		result = acpi_power_get_state(resource->device->handle,

				&state);

		if (result)

			return result;

		if (state != ACPI_POWER_RESOURCE_STATE_ON)

			return -ENOEXEC;

	}

	/* Update the power resource's _device_ power state */

	resource->device->power.state = ACPI_STATE_D0;
@@ -258,7 +246,7 @@ static int acpi_power_on(acpi_handle handle, struct acpi_device *dev) 


static int acpi_power_off_device(acpi_handle handle, struct acpi_device *dev)

{

	int result = 0, state;

	int result = 0;

	acpi_status status = AE_OK;

	struct acpi_power_resource *resource = NULL;

	struct list_head *node, *next;
@@ -293,18 +281,6 @@ static int acpi_power_off_device(acpi_handle handle, struct acpi_device *dev) 
	if (ACPI_FAILURE(status))

		return -ENODEV;



	if (!acpi_power_nocheck) {

		/*

		 * If acpi_power_nocheck is set, it is unnecessary to check

		 * the power state after power transition.

		 */

		result = acpi_power_get_state(handle, &state);

		if (result)

			return result;

		if (state != ACPI_POWER_RESOURCE_STATE_OFF)

			return -ENOEXEC;

	}



	/* Update the power resource's _device_ power state */

	resource->device->power.state = ACPI_STATE_D3;