[ 32/79] ACPI / PM: Do not execute _PS0 for devices without _PSC during initialization

From: Greg Kroah-Hartman
Date: Tue Jun 11 2013 - 16:14:55 EST

3.9-stable review patch. If anyone has any objections, please let me know.


From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>

commit 7cd8407d53ef5fb0280fcbe34f42311472f90feb upstream.

Commit b378549 (ACPI / PM: Do not power manage devices in unknown
initial states) added code to force devices without _PSC, but having
_PS0 defined in the ACPI namespace, into ACPI power state D0 by
executing _PS0 for them. That turned out to break Toshiba P870-303,
however, so revert that code.

References: https://bugzilla.kernel.org/show_bug.cgi?id=58201
Reported-and-tested-by: Jerome Cantenot <jerome.cantenot@xxxxxxxxx>
Tracked-down-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/acpi/device_pm.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -269,11 +269,13 @@ int acpi_bus_init_power(struct acpi_devi
if (result)
return result;
} else if (state == ACPI_STATE_UNKNOWN) {
- /* No power resources and missing _PSC? Try to force D0. */
+ /*
+ * No power resources and missing _PSC? Cross fingers and make
+ * it D0 in hope that this is what the BIOS put the device into.
+ * [We tried to force D0 here by executing _PS0, but that broke
+ * Toshiba P870-303 in a nasty way.]
+ */
state = ACPI_STATE_D0;
- result = acpi_dev_pm_explicit_set(device, state);
- if (result)
- return result;
device->power.state = state;
return 0;

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