ACPI / PM: Make __acpi_bus_get_power() cover D3cold correctly

After recent changes of the ACPI device power states definitions, if
power resources are not used for the device's power management, the
state returned by __acpi_bus_get_power() cannot exceed D3hot, because
the return values of _PSC are 0 through 3.  However, if the _PR3
method is not present for the device and _PS3 returns 3, we have to
assume that the device is in D3cold, so the value returned by
__acpi_bus_get_power() in that case should be 4.

Similarly, acpi_power_get_inferred_state() should take the power
resources for the D3hot state into account in general, so that it
can return 3 if those resources are "on" or 4 (D3cold) otherwise.

Fix the the above two issues and make sure that if both _PSC and
_PR3 are present for the device, the power resources listed by _PR3
will be used to determine if the number 3 returned by _PSC is meant
to represent D3cold or D3hot.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

drivers/acpi/bus.c

@@ -202,37 +202,44 @@ static const char *state_string(int state)
 
 static int __acpi_bus_get_power(struct acpi_device *device, int *state)
 {
-	int result = 0;
-	acpi_status status = 0;
-	unsigned long long psc = 0;
+	int result = ACPI_STATE_UNKNOWN;
 
 	if (!device || !state)
 		return -EINVAL;
 
-	*state = ACPI_STATE_UNKNOWN;
+	if (!device->flags.power_manageable) {
+		/* TBD: Non-recursive algorithm for walking up hierarchy. */
+		*state = device->parent ?
+			device->parent->power.state : ACPI_STATE_D0;
+		goto out;
+	}
 
-	if (device->flags.power_manageable) {
 	/*
 	 * Get the device's power state either directly (via _PSC) or
 	 * indirectly (via power resources).
 	 */
-		if (device->power.flags.power_resources) {
-			result = acpi_power_get_inferred_state(device, state);
-			if (result)
-				return result;
-		} else if (device->power.flags.explicit_get) {
-			status = acpi_evaluate_integer(device->handle, "_PSC",
-						       NULL, &psc);
+	if (device->power.flags.explicit_get) {
+		unsigned long long psc;
+		acpi_status status = acpi_evaluate_integer(device->handle,
+							   "_PSC", NULL, &psc);
 		if (ACPI_FAILURE(status))
 			return -ENODEV;
-			*state = (int)psc;
+
+		result = psc;
 	}
-	} else {
-		/* TBD: Non-recursive algorithm for walking up hierarchy. */
-		*state = device->parent ?
-			device->parent->power.state : ACPI_STATE_D0;
+	/* The test below covers ACPI_STATE_UNKNOWN too. */
+	if (result <= ACPI_STATE_D2) {
+	  ; /* Do nothing. */
+	} else if (device->power.flags.power_resources) {
+		int error = acpi_power_get_inferred_state(device, &result);
+		if (error)
+			return error;
+	} else if (result == ACPI_STATE_D3_HOT) {
+		result = ACPI_STATE_D3;
 	}
+	*state = result;
 
+ out:
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] power state is %s\n",
 			  device->pnp.bus_id, state_string(*state)));
 

drivers/acpi/power.c

@@ -631,7 +631,7 @@ int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
 	 * We know a device's inferred power state when all the resources
 	 * required for a given D-state are 'on'.
 	 */
-	for (i = ACPI_STATE_D0; i < ACPI_STATE_D3_HOT; i++) {
+	for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++) {
 		list = &device->power.states[i].resources;
 		if (list->count < 1)
 			continue;