[Intel-gfx] [PATCH v7 1/2] ACPI / bus: Introduce a list of ids for "always present" devices

[Rafael J. Wysocki]

On Friday, April 21, 2017 12:42:31 PM Hans de Goede wrote:
> HI,
> 

[cut]

> >>> And in that path, which I seem to have overlooked before, the
> >>> acpi_set_device_status() call is too early for invoking
> >>> acpi_device_always_present(adev), so the latter should be called
> >>> directly from acpi_add_single_object() like
> >>>
> >>>       acpi_init_device_object(device, handle, type, sta);
> >>>       if (acpi_device_always_present(adev))
> >>>           acpi_set_device_status(adev, ACPI_STA_DEFAULT);
> >>
> >> That is not necessary, the place(s) where we care about status being
> >> fixed-up for always-present devices, so that they get scanned / their
> >> platform device initiated, is in acpi_bus_attach() which
> >> already calls acpi_bus_get_status() and thus gets the
> >> acpi_device_always_present() check applied before checking.
> >>
> >> For hotplugged devices there are acpi_scan_bus_check and
> >> acpi_scan_device_check but those both also already call
> >> acpi_bus_get_status() before checking adev->status.
> > 
> > OK
> > 
> > Which probably means that we don't need to initialize adev->status
> > in acpi_init_device_object() to anything meaningful, do we?
> 
> Right, I don't think that is necessary. But maybe it is necessary
> for some special cases (e.g. power resources) ?

For power resources _STA is defined differently at all and we don't
even call acpi_add_single_object() for them. :-)

Are there any other special cases in which that may matter?

Thanks,
Rafael