Re: [PATCH v3 03/11] platform/x86/intel/ifs: Create device for Intel IFS (In Field Scan)

Greg KH
2022-04-20T07:49:20Z

On Tue, Apr 19, 2022 at 03:28:26PM -0700, Dan Williams wrote:
> On Tue, Apr 19, 2022 at 11:09 AM Dan Williams <dan.j.williams@intel.com> wrote:
> >
> > On Tue, Apr 19, 2022 at 9:48 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Tue, Apr 19, 2022 at 09:38:51AM -0700, Tony Luck wrote:
> > > > The initial implementation of IFS is model specific. Enumeration is
> > > > via a combination of family-model-stepping and a check for a bit in the
> > > > CORE_CAPABILITIES MSR.
> > > >
> > > > Linux has handled this lack of enumeration before with a code stub to
> > > > create a device. See arch/x86/kernel/pmem.c. Use the same approach
> > > > here.
> > >
> > > Ick, why? Why not just create a simple virtual device and use that? Do
> > > you really want to bind a driver to this? Or do you already "know" the
> > > only driver that you have will bind to this?
> >
> > With the realization that there may be multiple instances of an
> > IFS-like capability going forward, and that ideally those capabilities
> > would move away from a CPU capability bit to an ACPI description, then
> > it seemed to me that a simulated platform_device for this is a
> > reasonable fit. I.e. when / if an ACPI _HID is assigned for this
> > capability the same platform_driver can be reused for those instances.
>
> Turns out the ACPI enumeration for this may not materialize, so this
> can indeed move to a simple / driver-less device.

Hey, see, doing extra work now was not a good idea :)