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Message-ID: <07443b54-2973-7990-e749-66dd7fb4e499@linux.intel.com>
Date:   Wed, 4 Jan 2023 17:51:19 -0600
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Subject: Re: [RFC PATCH 09/14] sound: usb: Introduce QC USB SND offloading
 support
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To:     Wesley Cheng <quic_wcheng@quicinc.com>,
        srinivas.kandagatla@linaro.org, mathias.nyman@intel.com,
        perex@perex.cz, broonie@kernel.org, lgirdwood@gmail.com,
        andersson@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        gregkh@linuxfoundation.org, Thinh.Nguyen@synopsys.com,
        bgoswami@quicinc.com, tiwai@suse.com, robh+dt@kernel.org,
        agross@kernel.org
Cc:     devicetree@vger.kernel.org, alsa-devel@alsa-project.org,
        linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, quic_jackp@quicinc.com,
        quic_plai@quicinc.com
References: <20221223233200.26089-1-quic_wcheng@quicinc.com>
 <20221223233200.26089-10-quic_wcheng@quicinc.com>
From:   Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
In-Reply-To: <20221223233200.26089-10-quic_wcheng@quicinc.com>
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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?

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