[Sound-open-firmware] SOF firmware and topology files

[Pierre-Louis Bossart]

> Mark, I'm currently putting together / testing the sof ucm for Dell and Lenovo devices.
> Unfortunately I've not yet received the X1 (it is shipped to me). So ucm's for
> Dell and Lenovo will be in alsa-ucm-conf repository, Jaroslav has already done
> Some differentiation to handle Lenove differences.
> 
> Pierre, actually I'm not sure how the topology differentiation will be done?
> So for example can we load different topology in these 2 manufacturers device?
> So if it is just overwriting the new topology with same name, how to differentiate?

The topology should change only if the firmware changed, e.g. with the 
addition of a processing, path or secret sauce that's not in the default 
firmware released by Intel.

We have a default topology file path which can be modified with a kernel 
module parameter (see in sof-pci-dev.c), and we could also add DMI 
quirks to do this change as well. The file name would be identical, just 
located in a different directory (and not necessarily in 
/lib/firmware/intel/sof-tplg).

If an OEM decided to make changes to the topology, I'd guess they are on 
the hook to provide such changes to downstream distros? I am not sure we 
can manage all possible variations in a central repo, it's hard enough 
to provide all the default pieces already...