ACPI: Drop parent field from struct acpi_device

The parent field in struct acpi_device is, in fact, redundant,
because the dev.parent field in it effectively points to the same
object and it is used by the driver core.

Accordingly, the parent field can be dropped from struct acpi_device
and for this purpose define acpi_dev_parent() to retrieve a parent
struct acpi_device pointer from the dev.parent field in struct
acpi_device.  Next, update all of the users of the parent field
in struct acpi_device to use acpi_dev_parent() instead of it and
drop it.

While at it, drop the ACPI_IS_ROOT_DEVICE() macro that is only used
in one place in a confusing way.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Punit Agrawal <punit.agrawal@bytedance.com>

1 files changed, 10 insertions, 9 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 2b7e08d54c3f..028d8d14cd44 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -74,6 +74,7 @@ static int acpi_dev_pm_explicit_get(struct acpi_device *device, int *state)
  */
 int acpi_device_get_power(struct acpi_device *device, int *state)
 {
+	struct acpi_device *parent = acpi_dev_parent(device);
 	int result = ACPI_STATE_UNKNOWN;
 	int error;
 
@@ -82,8 +83,7 @@ int acpi_device_get_power(struct acpi_device *device, int *state)
 
 	if (!device->flags.power_manageable) {
 		/* TBD: Non-recursive algorithm for walking up hierarchy. */
-		*state = device->parent ?
-			device->parent->power.state : ACPI_STATE_D0;
+		*state = parent ? parent->power.state : ACPI_STATE_D0;
 		goto out;
 	}
 
@@ -122,10 +122,10 @@ int acpi_device_get_power(struct acpi_device *device, int *state)
 	 * point, the fact that the device is in D0 implies that the parent has
 	 * to be in D0 too, except if ignore_parent is set.
 	 */
-	if (!device->power.flags.ignore_parent && device->parent
-	    && device->parent->power.state == ACPI_STATE_UNKNOWN
-	    && result == ACPI_STATE_D0)
-		device->parent->power.state = ACPI_STATE_D0;
+	if (!device->power.flags.ignore_parent && parent &&
+	    parent->power.state == ACPI_STATE_UNKNOWN &&
+	    result == ACPI_STATE_D0)
+		parent->power.state = ACPI_STATE_D0;
 
 	*state = result;
 
@@ -159,6 +159,7 @@ static int acpi_dev_pm_explicit_set(struct acpi_device *adev, int state)
  */
 int acpi_device_set_power(struct acpi_device *device, int state)
 {
+	struct acpi_device *parent = acpi_dev_parent(device);
 	int target_state = state;
 	int result = 0;
 
@@ -191,12 +192,12 @@ int acpi_device_set_power(struct acpi_device *device, int state)
 		return -ENODEV;
 	}
 
-	if (!device->power.flags.ignore_parent && device->parent &&
-	    state < device->parent->power.state) {
+	if (!device->power.flags.ignore_parent && parent &&
+	    state < parent->power.state) {
 		acpi_handle_debug(device->handle,
 				  "Cannot transition to %s for parent in %s\n",
 				  acpi_power_state_string(state),
-				  acpi_power_state_string(device->parent->power.state));
+				  acpi_power_state_string(parent->power.state));
 		return -ENODEV;
 	}