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-e6b5d618af8...