[alsa-devel] [RFC 00/10] Enable HDA Codec support on Intel Platforms (Series2)

[Vinod Koul]

On Fri, Dec 01, 2017 at 09:03:25PM +0100, Takashi Iwai wrote:
> > >> FIXME:
> > >> - KConfig changes does not look right, but I could not think of any proper
> > >>    way without making changes into legacy HDA codec driver. So need some
> > >>    help on this topic.
> > >
> > > And this is another big issue.  As long as you don't allow build both,
> > > it never flies with distros, and it means no dramatic improvement of
> > > the situation, either.
> > >
> > > IOW, we have to make the codec driver working on both controller/bus
> > > implementations, and it essentially means to rewrite the HD-audio
> > > codec plumbing code.  Currently, it's a kind of half-baked state, and
> > > we need to cast to unified form.
> > 
> > Before going into codec support, should we first deal with the
> > selection of the ASoC/Legacy mode for the controller side of things?
> > Even with basic HDMI/iDisp cases, we don't have a clean solution
> > today. When I worked on the late Joule platform, there was no fallback
> > mode which forced a recompilation depending on BIOS settings.
> > My understanding is that there is no support for multiple drivers
> > registering for the same PCI ID, I believe we'll have to define a
> > top-level wrapper which arbitrates internally based on BIOS settings
> > and user/distro preferences which mode is selected.
> 
> True, we need to sort out that.  But the selection of the card-level
> driver can be relatively easily done in a manual way, either via
> blacklisting or by common module options.  Currently AMDGPU and radeon
> drivers are in such situation, for example.
> 
> A common single switch, or at best the automatic arbitration would be
> preferred, of course, though.

The switch is again short term as we should progress and move towards one
solution whilst deprecating the other, so that way this makes a simple
solution and helps in transition, change flag defaults and deprecate.

-- 
~Vinod