On Fri, Dec 13, 2024 at 04:45:30PM +0100, Krzysztof Kozlowski wrote:
On 13/12/2024 16:35, Johan Hovold wrote:
On Fri, Dec 13, 2024 at 03:54:02PM +0100, Krzysztof Kozlowski wrote:
The address space in ADSP PAS (Peripheral Authentication Service) remoteproc node should point to the QDSP PUB address space (QDSP6...SS_PUB): 0x0680_0000 with length of 0x10000.
0x3000_0000, value used so far, is the main region of CDSP and was simply copied from other/older DTS.
Correct the base address and length, which also moves the node to different place to keep things sorted by unit address. The diff looks big, but only the unit address and "reg" property were changed. This should have no functional impact on Linux users, because PAS loader does not use this address space at all.
Fixes: 5f2a9cd4b104 ("arm64: dts: qcom: x1e80100: Add ADSP/CDSP remoteproc nodes") Cc: stable@vger.kernel.org
Why bother with backporting any of these when there is no functional impact?
Not sure, I assumed someone might be using kernel DTS from stable branches in other projects. Kernel is the source of DTS and stable kernel has the DTS in both stable and fixed way. If 3rd party project keeps pulling always latest DTS from latest kernel, they will see so many ABI breaks and so many incompatibilities (we discussed it in Vienna) that they will probably curse their approach and say "never again". Using stable branch DTS could be a solution.
That makes some sense.
Such 3rd party project might actually use above device nodes in their drivers. It's just some of Linux kernel drivers which do not use them (other like PIL seems to use addresses).
But this is more questionable given that the current addresses are completely off in this case.
Plus DTS is used by 3rd party Linux kernels (out of tree), which while we do not care in a way of driving our development, but we do consider them possible users. They also might be relying on stable kernel branch for this.
Same here.
I realise this is a bit of a grey area, but given the size of the diffs and the no functional impact this could be an opportunity to try to uphold the stable kernel rules:
- It cannot be bigger than 100 lines, with context. - It must either fix a real bug that bothers people or just add a device ID.
Johan