[alsa-devel] [PATCH] ALSA: hda - Add DeviceID for Haswell HDA
tiwai at suse.de
Mon Jul 16 11:02:28 CEST 2012
At Mon, 16 Jul 2012 10:53:15 +0200,
Jaroslav Kysela wrote:
> Date 16.7.2012 10:40, Takashi Iwai wrote:
> > At Fri, 13 Jul 2012 19:48:22 +0200,
> > Jaroslav Kysela wrote:
> >> 00:03.0 0403: 8086:0c0c (rev 01)
> >> Subsystem: 8086:2010
> >> --
> >> 00:1b.0 0403: 8086:8c20 (rev 01)
> >> Subsystem: 8086:7270
> >> Perhaps, we may add also some code to penalize the HDMI only HDA bridges
> >> and allocate these cards on indexes 1+ by default (implement
> >> AZX_DCAPS_INDEX1) . Comments? I'll prepare a patch upon an agreement.
> > Having index=0 for analog would be nice in general, but I'm afraid
> > that it isn't always safe in the case of HD-audio (depending on the
> > implementation, though, of course):
> > - BIOS may disable the analog PCI part, e.g. if a device has only
> > HDMI/DP, or vice versa.
> > - There are already devices showing the same problem, e.g. AMD
> > on-board with AMD D-GPU, and users may have already added index
> > option for such.
> > IMO, we should provide a mechanism to advertise the preferred
> > configuration from the driver side without fiddling the index.
> > For example, exposing an info bit that this is digital-I/O only card,
> > and let alsa-lib choose another one as default (unless explicitly
> > specified).
> It's not a bad idea, but it would be good to have also "standard"
> plughw:0 and hw:0 devices available in the system.
You can omit ":0" part. Then alsa-lib should choose the right
> Do you think that the PCI ID / PCI subsystem ID check is not sufficient
> to determine the hw type before the codec probe?
Not really, because the controller ID doesn't always tell you whether
it's analog or digital.
Also, as mentioned, BIOS may enable/disable the PCI entries as it
wishes, thus you may get a system suddenly without index=0 in the
end if you forcibly set index=1 to HDMI/DP controller.
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