[PATCH v2 0/2] cxl: Allow passthrough decoders with >16K granularity

[Alison Schofield <alison.schofield@intel.com>]

Changes in v2:
- Rebased on Linux 7.2-rc1
- Only v1 feedback was from Sashiko and that was not an issue
Link to v1:
https://lore.kernel.org/linux-cxl/cover.1781136281.git.alison.schofield@intel.com/

Sashiko reported [1] that region setup rejects valid topologies
containing a passthrough decoder beneath a wide parent interleave. In
these configurations, a passthrough decoder can compute a granularity
above the 16K maximum encodable in the interleave granularity (IG)
field even though non-interleaving decoders do not consume that field.

The first patch avoids validating the interleave granularity of
non-interleaving decoders, encodes the IG field as a don't-care when
committing those decoders, and updates the sysfs ABI documentation
accordingly.

The second patch extends cxl-test with a topology that allows a CXL
unit test to cover this case.

A unit test update for this case is posted for review [2].

[1] https://lore.kernel.org/all/20260530002613.682E71F00893@smtp.kernel.org/
[2] https://lore.kernel.org/all/cover.1781136221.git.alison.schofield@intel.com/


Alison Schofield (2):
  cxl/region: Allow passthrough decoders with >16K granularity
  cxl/test: Add a 2-way 16K root decoder for passthrough testing

 Documentation/ABI/testing/sysfs-bus-cxl |  5 ++-
 drivers/cxl/core/hdm.c                  | 13 +++++--
 drivers/cxl/core/region.c               | 47 ++++++++++++++----------
 tools/testing/cxl/test/cxl.c            | 48 +++++++++++++++++++++++--
 4 files changed, 88 insertions(+), 25 deletions(-)


base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
-- 
2.37.3