Re: [PATCH v2 2/2] arm64: dts: qcom: kaanapali: fix traceNoC probe issue

[Leo Yan <leo.yan@arm.com>]

Hi Jie,

On Fri, Jun 26, 2026 at 10:03:41AM +0800, Jie Gan wrote:

[...]

> Hi Leo,
> 
> To be honest, I would prefer not to modify the interconnect platform driver.
> On some Qualcomm platforms, multiple itnoc devices reside within small
> blocks(one or more than one for each block) and are connected to a dummy
> source. In such cases, two ATIDs are allocated for a path (the dummy source
> and the itnoc), which is inefficient. This is why the itnoc platform driver
> created to avoid this waste.
> 
> The TraceNoC (called as AG TraceNoC) is a generic TraceNoC device which
> connected to multiple source and link devices, aggregating data from all
> source devices into a single output path.

As I said, it may be fragile to couple a specific device property (ATID)
to the AMBA driver.

You're now facing a case where a device cannot be registered as an AMBA
device, so it cannot use ATID. Likewise, I can imagine in future where a
device is registered as an AMBA device, but you don't want ATID.

> This device is implemented as an AMBA device but lacks proper hardware
> configuration. As a result, it must be handled in the driver as a
> workaround, which unfortunately breaks the original design intent.

Seems to me, it is not reasonable to pretend an AMBA device but AMBA
ID registers are absent.

How about add a new DT property ("qcom,tnoc-enable-atid") to force
enabling ATID?

Thanks,
Leo