> -----Original Message----- > From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> > Sent: Thursday, October 1, 2020 7:07 AM > To: Mark Brown <broonie@xxxxxxxxxx>; Ertman, David M > <david.m.ertman@xxxxxxxxx> > Cc: alsa-devel@xxxxxxxxxxxxxxxx; tiwai@xxxxxxx; > gregkh@xxxxxxxxxxxxxxxxxxx; Sridharan, Ranjani > <ranjani.sridharan@xxxxxxxxx>; parav@xxxxxxxxxx; jgg@xxxxxxxxxx > Subject: Re: [PATCH 0/6] Ancillary bus implementation and SOF multi-client > support > > > > >> 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 > > want for the way Linux describes devices is a sensible one for other > > operating systems so we don't want to put it into DT. Forcing things to > > be DT enumerated would just create needless ABIs. > > I agree the "DT enumerated" part should be removed. > > 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? The MFD bus also uses parts of the platform bus in the background, including platform_data and the such. We submitted a version of the RDMA/LAN solution using MFD and it was NACK'd by GregKH. -DaveE
