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, 3 insertions, 2 deletions

diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
index ab8a4e0191b1..9d69546db2a4 100644
--- a/drivers/acpi/acpi_amba.c
+++ b/drivers/acpi/acpi_amba.c
@@ -48,6 +48,7 @@ static void amba_register_dummy_clk(void)
 static int amba_handler_attach(struct acpi_device *adev,
 				const struct acpi_device_id *id)
 {
+	struct acpi_device *parent = acpi_dev_parent(adev);
 	struct amba_device *dev;
 	struct resource_entry *rentry;
 	struct list_head resource_list;
@@ -97,8 +98,8 @@ static int amba_handler_attach(struct acpi_device *adev,
 	 * attached to it, that physical device should be the parent of
 	 * the amba device we are about to create.
 	 */
-	if (adev->parent)
-		dev->dev.parent = acpi_get_first_physical_node(adev->parent);
+	if (parent)
+		dev->dev.parent = acpi_get_first_physical_node(parent);
 
 	ACPI_COMPANION_SET(&dev->dev, adev);