lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <c39df4c7-ea78-0505-a8d9-db41119fc977@quicinc.com>
Date:   Thu, 19 Oct 2023 11:42:22 -0700
From:   Wesley Cheng <quic_wcheng@...cinc.com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        <mathias.nyman@...el.com>, <gregkh@...uxfoundation.org>,
        <lgirdwood@...il.com>, <broonie@...nel.org>, <perex@...ex.cz>,
        <tiwai@...e.com>, <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <srinivas.kandagatla@...aro.org>, <bgoswami@...cinc.com>,
        <Thinh.Nguyen@...opsys.com>
CC:     <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <alsa-devel@...a-project.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v9 09/34] ASoC: qcom: qdsp6: Introduce USB AFE port to
 q6dsp

Hi Pierre,

On 10/18/2023 6:00 PM, Pierre-Louis Bossart wrote:
> 
> 
>>>>>> Specifically, the QC ADSP can support all potential endpoints that are
>>>>>> exposed by the audio data interface.  This includes, feedback
>>>>>> endpoints
>>>>>> (both implicit and explicit) as well as the isochronous (data)
>>>>>> endpoints.
>>>>>
>>>>> implicit feedback means support for capture. This is confusing...
>>>>>
>>>>
>>>> I mean, a USB device can expose a capture path, but as of now, we won't
>>>> enable the offloading to the audio DSP for it.  However, if we're
>>>> executing playback, and device does support implicit feedback, we will
>>>> pass that along to the audio DSP to utilize.
>>>
>>> Not following. Implicit feedback means a capture stream *SHALL* be
>>> started. Are you saying this capture stream is hidden and handled at the
>>> DSP level only? If yes, what prevents you from exposing the capture
>>> stream to userspace as well?
>>>
>>> I must be missing something.
>>>
>>
>> My understanding is that with implicit feedback endpoints, it allows for
>> another data endpoint in the opposite direction to be utilized as a
>> feedback endpoint (versus having to expose another EP, such as in the
>> case of explicit feedback).  For example, if we are enabling the
>> playback path (and the device does have a capture data ep) then the data
>> ep used for the capture path can be used.
> 
> That's right, so all the plumbing is enabled for the capture path...
> Making a decision to discard the data is very odd, all the work has
> already been done at lower levels, so why not expose the captured data?
> 

So that would be at the USB level, but from the audio DSP end, there are 
still things that need to be enabled to route the data properly.  For 
feedback endpoints, the data we're actually sending won't involve the 
audio streaming side of things on the DSP.

Thanks
Wesley Cheng

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ