[alsa-devel] [RFC PATCH 0/6] ALSA/HDA: abort probe when DMICs are detected

[Takashi Iwai]

On Fri, 24 May 2019 01:39:45 +0200,
Pierre-Louis Bossart wrote:
> 
> This is the second take on same problem of detecting when the HDaudio
> legacy driver can be used and when the SST or SOF drivers are
> required.
> 
> The previous attempt based on a the PCI Class information was a
> resounding failure and broke audio on Linus' laptop, so we need
> additional information to avoid enabling a DSP-based driver without a
> good reason to do so.
> 
> This patchset suggests the use of the NHLT information which *in
> theory* exposes DMIC endpoints. The legacy HDaudio driver cannot
> handle DMICs and will not provide any capture capabilities. Since it's
> typically the first one to probe due to the Makefile order, aborting
> the probe will let the PCI subsystem look for the next driver which
> hopefully will support this capability.
> 
> I tested this patch on 5 devices (SKL, KBL, APL, GLK, WHL), three
> without DMICs and two with, and the detection seems to work as
> planned. I would appreciate it if HDaudio integrators and folks at
> Google/Canonical/Endless can give this a try. As usual I expect that
> we will have to use quirks and work-arounds, but it'd be a better idea
> than a build-time mutual exclusion. We could also make this optional
> (Kconfig and/or module parameters) if people prefer to muck with
> blacklists.
> 
> Feedback and comments welcome!

The general idea and suggested implementation look almost good to me.
Of course we have to provide a way to override the default behavior in
case of buggy BIOS (I bet a drink for the existence of such :)


thanks,

Takashi