Re: [PATCH v6 3/4] dt-bindings: net: broadcom-bluetooth: Add pcm config

From: Marcel Holtmann
Date: Fri Nov 22 2019 - 07:34:11 EST


Hi Rob,

>> Add documentation for pcm parameters.
>>
>> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
>> ---
>>
>> Changes in v6: None
>> Changes in v5: None
>> Changes in v4: None
>> Changes in v3: None
>> Changes in v2: None
>
> Really? I'm staring at v2 that looks a bit different.
>
>> .../bindings/net/broadcom-bluetooth.txt | 16 ++++++++++
>> include/dt-bindings/bluetooth/brcm.h | 32 +++++++++++++++++++
>> 2 files changed, 48 insertions(+)
>> create mode 100644 include/dt-bindings/bluetooth/brcm.h
>>
>> diff --git a/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt b/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
>> index c749dc297624..8561e4684378 100644
>> --- a/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
>> +++ b/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
>> @@ -29,10 +29,20 @@ Optional properties:
>> - "lpo": external low power 32.768 kHz clock
>> - vbat-supply: phandle to regulator supply for VBAT
>> - vddio-supply: phandle to regulator supply for VDDIO
>> + - brcm,bt-sco-routing: PCM, Transport, Codec, I2S
>> + - brcm,bt-pcm-interface-rate: 128KBps, 256KBps, 512KBps, 1024KBps, 2048KBps
>> + - brcm,bt-pcm-frame-type: short, long
>> + - brcm,bt-pcm-sync-mode: slave, master
>> + - brcm,bt-pcm-clock-mode: slave, master
>
> Little of this seems unique to Broadcom. We already have some standard
> audio related properties for audio interfaces such as 'format',
> 'frame-master' and 'bitclock-master'. Ultimately, this would be tied
> into the audio complex of SoCs and need to work with the audio
> bindings. We also have HDMI audio bindings.
>
> Maybe sco-routing is unique to BT and still needed in some form though
> if you describe the connection to the SoC audio complex, then maybe
> not? I'd assume every BT chip has some audio routing configuration.

so we tried to generalize this some time before and failed to get a proper consensus.

In general I am with you that we should just expose generic properties from the attached audio codec, but nobody has come up with anything like that. And I think aligning all chip manufacturers will take some time.

Maybe in the interim we just use brcm,bt-pcm-int-params = [00 00 ..] as initially proposed.

Regards

Marcel