On Wed, Jan 20, 2016 at 02:40:08PM +0100, Tomasz Nowicki wrote:
[...]
- /* Root bridge device needs to be sure of parent ACPI type */
- ACPI_COMPANION_SET(&device->dev, device);
I do not understand why the code above is needed, can you elaborate please ?
This makes sure that device->dev can be identified as ACPI device, so we can use to_acpi_device_node() and assign companion safely below.
I do not follow. If you refer to the fwnode handle type, that is already set by ACPI core code (before acpi_pci_root_add() is called, in acpi_init_device_object()).
acpi_init_device_object() sets ACPI fwnode handle type only for "device", but not for "device->dev" which is what is passed as an argument to pci_create_root_bus().
Without ACPI_COMPANION_SET(&device->dev, device) here, no one can be sure if we have ACPI device in pci_create_root_bus().
Ok, got it. The question is whether this should be done in ACPI core instead (is there a reason why it should *not* be done ?), but I now understand your point.
Thanks, Lorenzo