Re: [PATCH V3 1/3] vfio, platform: add support for ACPI while detecting the reset driver

From: Arnd Bergmann
Date: Tue Mar 29 2016 - 05:27:14 EST

On Monday 28 March 2016 09:35:22 Sinan Kaya wrote:
> The code is using the compatible DT string to associate a reset driver with
> the actual device itself. The compatible string does not exist on ACPI
> based systems. HID is the unique identifier for a device driver instead.
> The change allows a driver to register with DT compatible string or ACPI
> HID and then match the object with one of these conditions.
> Rules for loading the reset driver are as follow:
> - ACPI HID needs match for ACPI systems
> - DT compat needs to match for OF systems
> Tested-by: Eric Auger <eric.auger@xxxxxxxxxx> (device tree only)
> Tested-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx> (ACPI only)
> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>

This really feels wrong for two reasons:

* device assignment of non-PCI devices is really special and doesn't
seem to make sense on general purpose servers that would be the target
for ACPI normally

* If there is indeed a requirement for ACPI to handle something like this,
it should be part of the ACPI spec, with a well-defined method of handling
reset, rather than having to add a device specific hack for each
device separately.