RE: RFC: (re-)binding the VFIO platform driver to a platform device

[Yoder Stuart-B08248]

> I am trying to understand what you are proposing here (example "DEVICE"
> can be handled by "DRIVER1" and "VFIO-PLATFORM-DRIVER"):
>  - By default drv->explicit_bind_only will be clear in all drivers.
>  - By default device->explicit_bind_only will also be clear for all
> devices.
>  - On boot, matching devices will bound to the respective driver (DEVICE
> >==> DRIVER1).
>    This will never bound with VFIO-PLATFORM-DRIVER. So far same as
> before.
>  - Via Sysfs interface set drv->explicit_bind_only for VFIO-PLATFORM-
> DRIVER.

No.  VFIO-PLATFORM-DRIVER is _always_ explicit_bind_only and thus will be
statically set in the driver.  See Kim's patch.

>  - Then for the devices user want, set device->explicit_bind_only.
>  - unbind DEVICE from DRIVER1
>  - bind DEVICE with VFIO-PLATFORM-DRIVER. This time it will be successful
> because (device->explicit_bind_only && drv->explicit_bind_only) is set.
>  - Now when done, unbind the DEVICE from VFIO-PLATFORM-DRIVER.
>  - Now user can re-bind the device with either DRIVER1 or VFIO-PLATFORM-
> DRIVER.
>  - Now once drv->explicit_bind_only is set in VFIO-PLATFORM-DRIVER, and a
> new device comes (device - hotplug) then can gets bound to matching drive
> and not with VFIO-PLATFORM-DRIVER.

Otherwise, it looks correct to me.

Stuart
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