Re: [PATCH 1/4] ALSA: hda: Skip i915 initialization on CNL/LKF-based platforms

[Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>]

On Thu, Feb 22, 2024 at 06:53:12PM +0100, Cezary Rojewski wrote:
> On 2024-02-22 6:24 PM, Ville Syrjälä wrote:
> > On Thu, Feb 22, 2024 at 06:06:11PM +0100, Cezary Rojewski wrote:
> > > Commit 78f613ba1efb ("drm/i915: finish removal of CNL") and its friends
> > > removed support for i915 for all CNL-based platforms. HDAudio library,
> > > however, still treats such platforms as valid candidates for i915
> > > binding. Update query mechanism to reflect changes made in drm tree.
> > > 
> > > At the same time, i915 support for LKF-based platforms has not been
> > > provided so remove them from valid binding candidates.
> 
> ...
> 
> > > @@ -127,15 +128,26 @@ static int i915_component_master_match(struct device *dev, int subcomponent,
> > >   /* check whether Intel graphics is present and reachable */
> > >   static int i915_gfx_present(struct pci_dev *hdac_pci)
> > >   {
> > > +	/* List of known platforms with no i915 support. */
> > > +	static struct pci_device_id denylist[] = {
> > > +		INTEL_CNL_IDS(NULL),
> > > +		INTEL_LKF_IDS(NULL),
> > > +		{ 0 }
> > > +	};
> > 
> > I thought these don't actually exist in the wild?
> 
> To my knowledge the opposite is true - while LKFs were shipped in limited
> number, they still were. I did ask few weeks ago my friends from Windows
> side about the support and they're still running full-scopes on HDMI
> endpoints on LKF platforms in their CIs. It seems the drm support is there
> though. Once you re-boot to linux we get -19 during probe().
> 
> In regard to CNL, the commit removing CNL-support left the IDs intact what's

I would prefer to go the other way around and remove the unused/unsupported
IDs entirely and for good.

> very handy to us - we have a lot of spare CNL boards for our validation
> purposes - CNL-based AudioDSP spans multiple platforms, e.g.:
> CNL/CFL/WHL/CML. The number of newer boards is lower, unfortunately.

Well, I do see your point here and you are not asking for us to add gfx
support back, but only help to have this protection here.

However I'm afraid that these entries in the list would only cause
further confusion. Couldn't they get defined inside your .c directly as
a const deny_list? so when we go there and remove the missing bits
of CNL we don't conflict or cause undersired issues to you.

> 
> 
> Kind regards,
> Czarek