Re: [RESEND] Amlogic DPCM audio card(s) speaker placement issue

[Jaroslav Kysela <perex@perex.cz>]

On 03. 01. 22 10:57, Jerome Brunet wrote:
> 
> On Sun 26 Dec 2021 at 18:30, Jaroslav Kysela <perex@perex.cz> wrote:
> 
>> On 26. 12. 21 12:43, Christian Hewitt wrote:
>>
>>> **** List of PLAYBACK Hardware Devices ****
>>> card 0: LIBRETECHCC [LIBRETECH-CC], device 0: fe.dai-link-0 (*) []
>>>    Subdevices: 1/1
>>>    Subdevice #0: subdevice #0
>>
>>> numid=12,iface=PCM,name='ELD',device=2
>>> numid=11,iface=PCM,name='IEC958 Playback Default',device=2
>>> numid=10,iface=PCM,name='IEC958 Playback Mask',device=2
>>> numid=9,iface=PCM,name='Playback Channel Map',device=2
>>> https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/amlogic/meson-gxl-s905x-libretech-cc.dts#L136-L188
>>
>> Have you tried to reorder the dai-link-# sections in DT? It appears to me that sound/soc/codecs/hdmi-codec.c / hdmi_codec_pcm_new() gets the internal PCM
>> device rather than the exported PCM device for the user space.
>>
>> If the DAI routing cannot be changed, then the hdmi-codec.c should be modified to export the correct device number for the user space:
>>
> 
> The DAI routing is dynamic, especially on the AXG series.
> There is actually two routing stages:
> 
> 1) Between the user interfaces (DMA) and the i2s/TDM encoders/decoders:
>     -> This is using DPCM
> 
> 2) Between the i2s/TDM encoders and the HDMI controller:
>     -> This is using Codec-to-Codec links
> 
> The problem exposed here is
>   - How to get the get the "Playback Channel Map" related to the pcm
>   device of a given playback ?

The PCM device exported to the user space should be able to export this 
information correctly. The kcontrols in hdmi-codec.c refers to an unknown 
(internal) PCM codec2codec device (from the user space view) which is created 
in the SoC layer.

It seems that kcontrols in hdmi-codec.c should not be created for the internal 
SoC PCMs. A new layer which translate the kcontrol handling between the 
exported (user space) PCM device and internal (SoC) PCM device is required.

Problematic code in hdmi_codec_pcm_new() / hdmi-codec.c:

- snd_pcm_add_chmap_ctls()
- kctl->id.device = rtd->pcm->device

						Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

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