Re: [PATCH v6 10/33] ASoC: qcom: qdsp6: Add USB backend ASoC driver for Q6

[Wesley Cheng]

Hi Konrad,

On 9/15/2023 5:34 PM, Konrad Dybcio wrote:
> On 16.09.2023 02:10, Wesley Cheng wrote:
> > Create a USB BE component that will register a new USB port to the ASoC USB
> > framework.  This will handle determination on if the requested audio
> > profile is supported by the USB device currently selected.
> >
> > Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> > ---
> [...]
>
> > +	ret = of_parse_phandle_with_fixed_args(node, "iommus", 1, 0, &args);
> > +	if (ret < 0)
> > +		data->priv.sid = -1;
> > +	else
> > +		data->priv.sid = args.args[0] & SID_MASK;
> SID masking is done in the devicetree.

Not sure I get this point, but let me explain the use case of this 
parameter, and maybe you can help clarify.

In this case, we are saving and passing the SID info so that the buffers 
being mapped within the QC offload driver can be communicated to the 
audio DSP.  So in short, the SID masking that is done here is just to 
extract the SID from the iommus property.

Thanks
Wesley Cheng