[alsa-devel] HDA Intel ALC889A optical optical spdif in

[René Rebe]

Hi,
On Apr 21, 2017, at 22:29, René Rebe <rene at exactcode.de> wrote:

> Hi,
> 
> On Apr 21, 2017, at 20:01, Takashi Iwai <tiwai at suse.de> wrote:
> 
>> On Fri, 21 Apr 2017 19:22:16 +0200,
>> René Rebe wrote:
>>> 
>>> On Apr 21, 2017, at 18:37, René Rebe <rene at exactcode.de> wrote:
>>> 
>>>> Hello again,
>>>> 
>>>> so I checked the MacBook schematics and it looks like the optical input should be directly connected to pin 47 (GPIO3/SPDIFIN)
>>>> 
>>>> Maybe EAPD get’s accidentally / wrongly enabled? - Maybe someone can point me how to double check this in ALSA?
>>> 
>>> I the meantime I finally figured out how this debug verb setting should work via:
>>> 
>>> # hda-verb /dev/snd/hwC0D0 0x14 0x70C 0
>>> nid = 0x14, verb = 0x70c, param = 0x0
>>> value = 0x0
>>> # hda-verb /dev/snd/hwC0D0 0x15 0x70C 0
>>> nid = 0x15, verb = 0x70c, param = 0x0
>>> value = 0x0
>>> 
>>> which made no difference either, and the ALC889 spec reads “when pin
>>> widget  SPDIF-IN is not connected via the programming configuration
>>> register.”
>>> 
>>> Could that be a missing bit?
>>> 
>>> Any pointer or verbs I should poke welcome :-/
>> 
>> Well, from the codec POV, the SPDIF in is straightly connected from
>> the pin to the audio in widget, so there should be no special thing
>> there.  The possibly missing setup is the vendor-specific things, and
>> Apple has been implementing the stuff always in a wild manner,
>> e.g. doing via VREF, GPIO or whatever.
> 
> Did you check anything in this proc file codec setup I posted?
> 
> As far as I can see on schematics for the MacBook (e.g.. google returned
> a APPLE_M42C_FA522_Macbook.pdf) the optical module RX output
> seems to be “directly" attached to the codec’s spdif-in pin.
> 
> Yet on both, the MacBook as well on the MacBook Pro
> I found no way to get any digital input captured. The same setup
> works when booted in macOS, as well as when I plug
> in my digital audio source into my aging maudio delta 1010,
> with Linux, which, however, I do not want to continuously use for
> this setup, …
> 
> It’s a pity, I don’t think there are so many other laptops with
> optical input :-/

For the MacBook Pro I googled the i/o board schematics
(820-2273 LIO.pdf) - unfortunately some lines are crippled / strange
rectangles. However, it most likely spdif-in is directly connected like in
the MacBook. The schematic calls the codec a ALC885 instead of the
ALC889A as indicated by ALSA, …  And the schematic labels the
codec spdif innput pin SPDIFI/EAPD/MIDI-I/DMIC-R. However,
the public ALC885 spec has a footnote “MIDI function is not
supported as pins 46 and 48 are assigned as S/PDIF IO” and for the
DMIC: “pin 47 can be configured to support a secondary digital mic
input (DMIC-R). It is supported via a customized Realtek driver”

It is not getting better, …

	:-/

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