Re: [PATCH v7 0/5] Fix traceNoC probe issue on multiple QCOM platforms

[Leo Yan]

On Tue, Nov 10, 2026 at 09:46:43AM -0600, Rob Herring wrote:
> On Tue, Nov 10, 2026 at 09:21:13AM +0800, Jie Gan wrote:
> > The CoreSight TNOC (Trace Network-On-Chip) binding so far only allowed the
> > two-string AMBA form "qcom,coresight-tnoc", "arm,primecell". That form
> > forces the device onto the AMBA bus, where the driver must read the
> > peripheral ID from the device registers during probe. On several QCOM
> > platforms this AMBA peripheral-ID probing fails, so the traceNoC device
> > never probes and its trace path is unavailable.
> 
> But it works fine on some platforms? We have a property to override the 
> peripheral-ID which would solve your issue. That would be much simpler 
> and avoid the ABI break on any of the working platforms.

Looking back at the earlier discussion [1], Jie in v2 already proposed
"arm,primecell-periphid". Questions about AMBA IDs and ATID handling got
mixed together. The series later moved towards platform-device probing,
then became current shape.

Hope we make the right decision on arm,primecell-periphid this time.

Anyway, I'd like to apologise to Jie for all the back and forth.

Thanks,
Leo

[1] https://lore.kernel.org/linux-arm-kernel/9432df20-08bf-4134-b4b9-e6b5d618af81@xxxxxxxxxxxxxxxx/