Re: [PATCH v5 0/3] Switch Arm CCA to use an auxiliary device instead of a platform device

[Aneesh Kumar K.V <aneesh.kumar@kernel.org>]

Greg KH <gregkh@linuxfoundation.org> writes:

> On Thu, May 14, 2026 at 03:10:27PM +0530, Aneesh Kumar K.V (Arm) wrote:
>> As discussed here:
>> https://lore.kernel.org/all/20250728135216.48084-12-aneesh.kumar@kernel.org
>> 
>> The general feedback was that a platform device should not be used when
>> there is no underlying platform resource to represent. The existing CCA
>> support uses a platform device solely to anchor the TSM interface in the
>> device hierarchy, which is not an appropriate use of a platform device.
>> Use an auxiliary device instead to track CCA support.
>
> Why an aux device?  If this has no platform resources, please use the
> faux bus support instead, that is what it is there for.  aux devices are
> used when you are sharing a real resource among different "child"
> drivers, and need some way to coordinate that sharing.  If you have no
> resources, there's nothing to share, so no need for the complexity that
> aux gives you, just use faux instead.
>

We did discuss between faux an auxiliary devices early here
https://lore.kernel.org/all/20251010135922.GC3833649@ziepe.ca

To summarize auxiliary device was choosen so that we can do module
autoloading.

-aneesh