ALSA HDMI output not detected

ALSA HDMI output not detected

[samuelchemla]

Hi guys,

I opened a bug about HDMI sound output not detected on an NVIDIA optimus 
laptop.
I don't know if HDMI sound card detection is up to ALSA, the kernel or 
the video driver.
Could anyone give me a clue so the bug can be routed to its correct 
destination?
Link to the bug: 
https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1377653

Regards,
Sam

Re: ALSA HDMI output not detected

[Takashi Iwai]

At Wed, 22 Oct 2014 19:46:58 +0200,
samuelchemla@orange.fr wrote:
> 
> Hi guys,
> 
> I opened a bug about HDMI sound output not detected on an NVIDIA optimus 
> laptop.
> I don't know if HDMI sound card detection is up to ALSA, the kernel or 
> the video driver.

Actually all of three are involved fairly tightly.

> Could anyone give me a clue so the bug can be routed to its correct 
> destination?
> Link to the bug: 
> https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1377653

You should start checking EDID on the video side and ELD on the audio
side.  ALSA driver shows the connection and ELD status in proc files
and control elements.  If EDID is given, but ELD (or monitor
connection state) isn't, usually it's a video driver problem, e.g. the
audio register bit isn't set properly.


Takashi

Re: ALSA HDMI output not detected

[samuelchemla]

Hi,

there is no ELD file in /proc/asound nor /proc/asound/card0
On the EDID side, do you mean any EDID from any HDMI screen ?
I thought EDID file was screen dependant.
I know the screen is HDMI sound capable because I am using it with a 
raspberry without problem... :-)

Regards,
Sam

On 23/10/2014 18:14, Takashi Iwai wrote:
> At Wed, 22 Oct 2014 19:46:58 +0200,
> samuelchemla@orange.fr wrote:
>> Hi guys,
>>
>> I opened a bug about HDMI sound output not detected on an NVIDIA optimus
>> laptop.
>> I don't know if HDMI sound card detection is up to ALSA, the kernel or
>> the video driver.
> Actually all of three are involved fairly tightly.
>
>> Could anyone give me a clue so the bug can be routed to its correct
>> destination?
>> Link to the bug:
>> https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1377653
> You should start checking EDID on the video side and ELD on the audio
> side.  ALSA driver shows the connection and ELD status in proc files
> and control elements.  If EDID is given, but ELD (or monitor
> connection state) isn't, usually it's a video driver problem, e.g. the
> audio register bit isn't set properly.
>
>
> Takashi