[alsa-devel] Incorrect name of PCM

[Takashi Iwai]

On Tue, 24 Jul 2018 05:17:22 +0200,
Christopher Head wrote:
> 
> On Mon, 23 Jul 2018 19:40:36 +0200
> Takashi Iwai <tiwai at suse.de> wrote:
> 
> > OK, then another possibility is a BIOS bug.  BIOS declares the pin as
> > HDMI incorrectly although it's a SPDIF.
> 
> That would appear to be the case. According to the VT1708S datasheet,
> the typical application is for digital output widget node 0x12,
> attached to pin complex node 0x20, to be used for S/PDIF, and digital
> output widget node 0x15, attached to pin complex node 0x21, to be used
> for HDMI. The datasheet’s default values for the Configuration Default
> words for the two pin complex nodes agree with that configuration. This
> also appears to be how my motherboard is configured.
> 
> However, I have attached /proc/asound/card0/codec#0; this file states
> that node 0x20 is HDMI and 0x21 is S/PDIF, and having decoded the raw
> words based on the Intel HDA specification revision 1.0a, I agree that
> the kernel is decoding them correctly. I assume the kernel driver
> doesn’t change these words, which means the information I’m seeing
> there, since it’s not the codec default, must have been put there by
> the BIOS, apparently erroneously.
> 
> Is this something that the ALSA project wants to (or even can) add a
> quirk for? I am already running the most recent BIOS available.

You just need to disable the unused HDMI pin by setting the pin config
value, even without recompiling drivers.  It can be overridden by
"patch" file, as mentioned in Documentation/sound/hd-audio/notes.rst.


Takashi