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

[Pan, Xiuli]

On 6/5/2018 20:25, Pierre-Louis Bossart wrote:
> On 6/5/18 3:01 AM, Pan, Xiuli wrote:
>>
>>
>> On 6/5/2018 15:52, Liam Girdwood wrote:
>>> On Tue, 2018-06-05 at 13:22 +0800, Pan, Xiuli wrote:
>>>> On 6/5/2018 12:35, Pierre-Louis Bossart wrote:
>>>>>
>>>>> On 06/04/2018 08:19 PM, Keyon Jie wrote:
>>>>>>
>>>>>> On 2018年06月04日 23:08, Pierre-Louis Bossart wrote:
>>>>>>> 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,
>>>>>> Actually not accurate here, there may still be audio which is coming
>>>>>> from Tx of the same SSP port, only the audio data from SDI of SSP
>>>>>> will be ignored.
>>>>> which is a brilliant feature if you need the microphone data for e.g.
>>>>> hangouts or similar VoIP... As discussed with Liam, this is fine with
>>>>> a kcontrol as long as it's not exposed to end users.
>>>>>
>>>>>>> this will generate support issues. LBM is only useful in test 
>>>>>>> modes,
>>>>>>> and there's no problem generating test configurations.
>>>>>> I agree to add LBM kcontrol for each SSP here, similar to kinds of
>>>>>> kcontrols exported by codec driver, they are only for expert, end
>>>>>> user should not touch them if they can't understand it.
>>>>> Good luck with that. We have to add some protection here
>>>> OK, let me have a summary here:
>>>> 1. LBM switch should be bind to each SSP, no question about this.
>>>> 2. LBM switch should be protect or hidden to end user: debugfs or root
>>>> access kcontrol (curious about if ALSA have such interface)
>>> You could create a debugFS interface that could enable/disable 
>>> global SOF driver
>>> debug mode. Once this is enabled the kcontrols for "DBG SSPn 
>>> Loopback" would
>>> then work.
>>>
>>>> For the Kcontrol I have some question below:
>>>>
>>>>>> Thanks,
>>>>>> ~Keyon
>>>>>>
>>>>>>>>> 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.
>>>> I tried to add mixer for AIF widgets, but DAPM is designed not to 
>>>> expose
>>>> a kcontrol for AIF widgets.
>>> ok, then just create a new vendor tuple that can be attached as 
>>> private data to
>>> the DAI topology object. This tuple "flag" creates a kcontrol in the 
>>> driver that
>>> uses the DAI component ID. In the FW dai.c handles the command and 
>>> does the LBM
>>> or whatever.
>> May I use the token SOF_TKN_DAI_LBM to control the driver to create 
>> the kcontrol?
>> Another question is about how to create a kcontorl only expose to 
>> root only?
>> Or we may only create the kcontrol in #if DEBUG ?
>
> kernel module parameter to avoid recompilation, e.g. 'expert-mode=1'?
Discussed with Liam, we agreed to use a debugfs to set debug mode for 
SOF driver to control the LBM switch.

Thanks
Xiuli
>
>>
>> Thanks
>> Xiuli
>>>> I have seen one of patch in EIG kernel
>>>> [WORKAROUND] ASoC: dapm: fix stream directions for dsp_loopback links
>>>> What is this dsp_loopback means here.
>>>> Maybe I think we may add a dai_link widget for the switch.
>>> No idea, I've not seen it.
>>>
>>> Liam
>>>
>>>> Thanks
>>>> Xiuli
>>>>
>>>>>>>> Liam
>>>>
>>
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