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Date: Tue, 23 Apr 2024 16:59:56 +0100
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Subject: Re: [PATCH v2 0/4] ASoC: qcom: display port changes
To: Johan Hovold <johan@kernel.org>
Cc: broonie@kernel.org, perex@perex.cz, tiwai@suse.com, lgirdwood@gmail.com,
 alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
 Bjorn Andersson <quic_bjorande@quicinc.com>
References: <20240422134354.89291-1-srinivas.kandagatla@linaro.org>
 <ZieihZRKe7OtP-nV@hovoldconsulting.com>
 <92b02fd3-5eba-42a7-a166-21b14724b10c@linaro.org>
 <ZifMlc_rLV6_LhUy@hovoldconsulting.com>
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From: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
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On 23/04/2024 15:58, Johan Hovold wrote:
>> It is absolutely possible to run all the streams in parallel from the
>> Audio hardware and DSP point of view.
>>
>> One thing to note is, On Qualcomm DP IP, we can not read/write registers
>> if the DP port is not connected, which means that we can not send data
>> in such cases.
>>
>> This makes it challenging to work with sound-servers like pipewire or
>> pulseaudio as they tend to send silence data at very early stages in the
>> full system boot up, ignoring state of the Jack events.
> This bit sounds like it can and should be worked around by the driver to
> avoid hard-coding policy which would prevent use cases such as the ones
> mentioned above.
This is not simple as you say. We have to fit these into a proper DPCM.
Either we have a dummy Backend connected for each of these pcm 
sub-devices when DP port is not connected and then switch back to DP 
when its connected.

Or somehow find a way to not let the pipewire talk to devices which are 
not connected.


thanks,
srini