linux-kernel - Re: [PATCH v7 09/33] ASoC: qdsp6: q6afe: Increase APR timeout

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Message-ID: <29584061-a7e9-5db4-a024-eaf7774a03dd@quicinc.com>
Date:   Wed, 27 Sep 2023 13:01:40 -0700
From:   Wesley Cheng <quic_wcheng@...cinc.com>
To:     Mark Brown <broonie@...nel.org>
CC:     <mathias.nyman@...el.com>, <gregkh@...uxfoundation.org>,
        <lgirdwood@...il.com>, <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>, <linux-kernel@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <alsa-devel@...a-project.org>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH v7 09/33] ASoC: qdsp6: q6afe: Increase APR timeout

Hi Mark,

On 9/27/2023 7:50 AM, Mark Brown wrote:
> On Thu, Sep 21, 2023 at 02:48:19PM -0700, Wesley Cheng wrote:
>> For USB offloading situations, the AFE port start command will result in a
>> QMI handshake between the Q6DSP and the main processor.  Depending on if
>> the USB bus is suspended, this routine would require more time to complete,
>> as resuming the USB bus has some overhead associated with it.  Increase the
>> timeout to 3s to allow for sufficient time for the USB QMI stream enable
>> handshake to complete.
> 
> ...
> 
>> -#define TIMEOUT_MS 1000
>> +#define TIMEOUT_MS 3000
> 
> That seems worryingly large but if it's what the hardware/firmware needs
> I guess there's nothing doing - even the 1s that's being replaced would
> be nasty if we ever actually hit it.

I may have gone overkill with the delay, but when I measured the 
duration of the AFE start command it took ~1.5-2s.  It has to also 
account for the overhead within handling the USB QMI request in the 
qc_audio_offload driver.

Thanks
Wesley Cheng