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    SubjectRe: [RFC PATCH 09/14] sound: usb: Introduce QC USB SND offloading support
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    Hi Pierre,

    On 1/4/2023 3:51 PM, Pierre-Louis Bossart wrote:
    >
    >
    > On 12/23/22 17:31, Wesley Cheng wrote:
    >> Several Qualcomm SoCs have a dedicated audio DSP, which has the ability to
    >> support USB sound devices. This vendor driver will implement the required
    >> handshaking with the DSP, in order to pass along required resources that
    >> will be utilized by the DSP's USB SW. The communication channel used for
    >> this handshaking will be using the QMI protocol. Required resources
    >> include:
    >> - Allocated secondary event ring address
    >> - EP transfer ring address
    >> - Interrupter number
    >>
    >> The above information will allow for the audio DSP to execute USB transfers
    >> over the USB bus. It will also be able to support devices that have an
    >> implicit feedback and sync endpoint as well. Offloading these data
    >> transfers will allow the main/applications processor to enter lower CPU
    >> power modes, and sustain a longer duration in those modes.
    >
    > Are you suggesting that the entire feedback loop be handled in the DSP?
    > It's not clear what "Offloading these data transfers" refers to, the
    > data part or the feedback path?
    >

    Yes, as mentioned in the cover letter response, we'll handle the
    feedback endpoints. (feedback eps are part of the audio data interface)

    > Comments are almost inexistent in this patch so it's hard to figure out
    > what it really does.
    >

    OK, will add some more comments.

    Thanks
    Wesley Cheng

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