[Sound-open-firmware] [PATCH 1/2] uapi: ipc: Add lbm in sof_ipc_dai_config

[Pierre-Louis Bossart]

On 6/4/18 4:26 AM, Liam Girdwood wrote:
> On Mon, 2018-06-04 at 16:58 +0800, Pan, Xiuli wrote:
>>>> diff --git a/src/include/uapi/ipc.h b/src/include/uapi/ipc.h
>>>> index 9b1063f..06498fb 100644
>>>> --- a/src/include/uapi/ipc.h
>>>> +++ b/src/include/uapi/ipc.h
>>>> @@ -345,7 +345,7 @@ struct sof_ipc_dai_config {
>>>>     
>>>>        /* physical protocol and clocking */
>>>>        uint16_t format;        /* SOF_DAI_FMT_ */
>>>> -    uint16_t reserved;      /* alignment */
>>>> +    uint16_t lbm;           /* loopback mode*/
>>>>     
>>>>
>>>
>>> loopback is not tied to HW config, it can be enabled/disable at runtime so
>>> hould use the standard IPC for component commands like volume.
>>
>> OK, this is done by suggestion from Pierre to not use a kcontrol but a
>> static topology token,
>> So if it is need to be runtime enable/disable. Then a kcontrol or a
>> debugfs should be used?
> 
> kcontrol is more flexible since we don't have to change topologies and they
> should come as standard with all SSP topologies.

I don't really agree here. If a user sets the loopback kcontrol there's 
no audio any more. "Be careful what you wish for" seems to apply here, 
this will generate support issues. LBM is only useful in test modes, and 
there's no problem generating test configurations.

> 
>> I tried to use kcontrol but did not know which widget to bind with in
>> the pipeline. The DAPM kcontrol has so many limit.
>> What would you suggest to do with it?
> 
> SSp port is represented by AIF widget ? If so, add a kcontrol to it.
> 
> Liam
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