From a2367807b8d2c0aca5afb92fead2537dcd3d10b0 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 22 Jan 2013 12:54:38 +0100 Subject: [PATCH] ACPI / PM: Make acpi_bus_init_power() more robust The ACPI specification requires the _PSC method to be present under a device object if its power state cannot be inferred from the states of power resources used by it (ACPI 5, Section 7.6.2). However, it also requires that (for power states D0-D2 and D3hot) if the _PSn (n = 0, 1, 2, 3) method is present under the device object, it also must be executed after the power resources have been set appropriately for the device to go into power state Dn (D3 means D3hot in this case). Thus it is not clear from the specification whether or not the _PSn method should be executed if the initial configuraion of power resources used by the device indicates power state Dn and the _PSC method is not present. The current implementation of acpi_bus_init_power() is based on the assumption that it should not be necessary to execute _PSn in the above situation, but experience shows that in fact that assumption need not be satisfied. For this reason, make acpi_bus_init_power() always execute _PSn if the initial configuration of device power resources indicates power state Dn. Reported-and-tested-by: Mika Westerberg Signed-off-by: Rafael J. Wysocki --- drivers/acpi/device_pm.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c index 43116cdbabf9..c87853f583d8 100644 --- a/drivers/acpi/device_pm.c +++ b/drivers/acpi/device_pm.c @@ -330,13 +330,23 @@ int acpi_bus_init_power(struct acpi_device *device) if (result) return result; - if (device->power.flags.power_resources) + if (state < ACPI_STATE_D3_COLD && device->power.flags.power_resources) { result = acpi_power_on_resources(device, state); + if (result) + return result; - if (!result) - device->power.state = state; + if (device->power.states[state].flags.explicit_set) { + char method[5] = { '_', 'P', 'S', '0' + state, '\0' }; + acpi_status status; - return result; + status = acpi_evaluate_object(device->handle, method, + NULL, NULL); + if (ACPI_FAILURE(status)) + return -ENODEV; + } + } + device->power.state = state; + return 0; } int acpi_bus_update_power(acpi_handle handle, int *state_p)