[PATCH 0/6] Ancillary bus implementation and SOF multi-client support

[Pierre-Louis Bossart]

On 10/1/20 10:24 AM, Mark Brown wrote:
> On Thu, Oct 01, 2020 at 09:07:19AM -0500, Pierre-Louis Bossart wrote:
> 
>>>> are controlled by DT/ACPI. The same argument applies for not using MFD
>>>> in this scenario as it relies on individual function devices being
>>>> physical devices that are DT enumerated.
> 
>>> MFD has no reliance on devices being DT enumerated, it works on systems
>>> that don't have DT and in many cases it's not clear that the split you'd
> 
> ...
> 
>> To the best of my knowledge, the part of 'individual function devices being
>> physical devices' is correct though. MFDs typically expose different
>> functions on a single physical bus, and the functions are separated out by
>> register maps. In the case where there's no physical bus/device and no
>> register map it's unclear how MFDs would help?
> 
> MFD doesn't care.  All MFD is doing is instantiating platform devices
> and providing mechanisms to pass resources through from the parent
> device to the child devices.  It doesn't really matter to it which if
> any combination of resources are being provided to the children or what
> the devices represent.

I have nothing against MFD, but if this boils down to platform devices 
we are back to the initial open "are platform devices suitable as 
children of PCI devices"? I've heard Greg say no for the last year and a 
half - and he just re-stated this earlier in this thread.