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>

2 files changed, 30 insertions, 23 deletions

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index a41be56c1cc0..adceafda9c17 100644
--- a/drivers/acpi/bus.c
+++ b/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) {
-                /*
-                 * 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 (ACPI_FAILURE(status))
-                                return -ENODEV;
-                        *state = (int)psc;
-                }
-        } else {
+        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;
+        }
+
+        /*
+         * Get the device's power state either directly (via _PSC) or
+         * indirectly (via power resources).
+         */
+        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;
+
+                result = psc;
+        }
+        /* 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)));
 
diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
index 0500f719f63e..dd6d6a3c6780 100644
--- a/drivers/acpi/power.c
+++ b/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;