[PATCH v2 0/3] ASoC: qcom: enable audio on stage-2 protected DSPs (mDSP)

[Ajay Kumar Nandam]

On platforms such as Qualcomm Shikra, audio is served by the modem DSP
(mDSP) rather than the ADSP. The mDSP runs in a stage-2 protected context
and cannot use the SMMU, so the PCM buffers it consumes must live in
reserved-memory carveouts that are handed to the consumer VMIDs via a
hypervisor (SCM) memory assignment. This series adds that access model to
the q6apm DAI driver and its binding, alongside the existing stage-1/SMMU
(iommus) path, which is left untouched.

The two access models are mutually exclusive: a node carries either
iommus (stage-1) or qcom,vmids (stage-2), enforced in both the binding
(oneOf) and the driver.

This supersedes all prior postings. The v1 was sent as multiple
independent series (VMID binding + driver, memory-region binding + DTS,
and a standalone carveout patch). Per review feedback from Mark Brown [1]
and Srinivas Kandagatla [2][3] the binding and driver patches are now
consolidated into a single series so they can be reviewed and merged
together.

Prior versions:
v1 (VMID binding + driver + GPR domain):
  https://lore.kernel.org/all/20260609064038.492641-1-ajay.nandam@xxxxxxxxxxxxxxxx/
v1 (memory-region binding + DTS):
  https://lore.kernel.org/all/20260618113509.2025881-1-ajay.nandam@xxxxxxxxxxxxxxxx/
v2 (carveout SCM assignment, standalone):
  https://lore.kernel.org/all/20260624123748.502781-1-ajay.nandam@xxxxxxxxxxxxxxxx/

[1] https://lore.kernel.org/all/97cab297-ef92-48dd-8331-71aac0b51538@xxxxxxxxxxxxx/
[2] https://lore.kernel.org/all/39e90d95-0bae-4eb8-96d4-6e39aae432b2@xxxxxxxxxx/
[3] https://lore.kernel.org/all/02eee0a8-8c0f-4b0c-acc2-05dc436e5a85@xxxxxxxxxx/

Changes since v1:
- Consolidate all three independent series (VMID binding + driver,
  memory-region binding, carveout assignment) into a single 3-patch
  series, as requested by Mark Brown [1] and Srinivas Kandagatla [2][3].
- binding: combine qcom,vmids property, memory-region, oneOf constraint,
  and dependentRequired into one binding patch since all changes go to
  the same YAML file.
- binding: rename DT property from qcom,vmid (singular) to qcom,vmids
  (plural) and expand the description to explain VMIDs, the hardware
  access model, and which platforms require this (Krzysztof [4][5],
  Srinivas [2]).
- binding: make iommus and qcom,vmids mutually exclusive via oneOf
  rather than keeping iommus unconditionally required (Krzysztof [4]).
- binding: correct the qcom,vmids description - SCM assignment replaces
  the buffer's owners with the supplied set, so the driver adds HLOS to
  the destination itself; reword to say so instead of "HLOS is always
  retained".
- binding: add uniqueItems to qcom,vmids.
- binding: add ranges to the reserved-memory example node.
- binding: fix qcom,vmids example from two separate cells to a single
  uint32 array.
- binding: make the qcom,vmids example self-contained by including the
  reserved-memory nodes the memory-region phandles point at.
- binding: document that all listed VMIDs and HLOS receive read-write
  access.
- driver (patch 2): merge SCM VMID assignment and carveout buffer
  allocation into a single bisect-safe patch. Move dest_domain stamping
  from every packet-allocation call site into the send helpers
  (q6apm_send_cmd_sync, audioreach_graph_send_cmd_sync,
  q6prm_send_cmd_sync) and the four async data-path sends. This
  centralizes domain routing at the send layer and avoids threading a
  dest_domain parameter through every alloc helper. Suggested by
  Srinivas Kandagatla.
- driver: rewrite commit messages to clearly state the problem, the
  platform, and why it fails without the fix (Srinivas [3]).
- driver: move SCM assign/unassign to probe/remove lifecycle matching
  upstream patterns (rmtfs_mem, qcom_q6v5_pas) instead of per-stream
  open/close.
- driver: guard the reserved-memory per-stream buffer size against
  size_t underflow when the pool is smaller than
  Q6APM_POOL_MAX_STREAMS * POS_BUFFER_BYTES.
- driver: bounds-check num_carveouts against Q6APM_MAX_CARVEOUTS before
  recording a runtime PCM carveout.
- driver: track SCM carveouts per-PCM and reclaim only the freed PCM's
  region in pcm_free, instead of unassigning every region; this also
  stops num_carveouts growing unbounded across new/free cycles.
- driver: log SCM unassign (reclaim-to-HLOS) failures and keep the
  region marked assigned so DSP-owned memory is never returned to the
  pool.
- driver: reject qcom,vmids and iommus present together at probe.
- driver: of_node_put() the iommus phandle args; checkpatch/style
  cleanups.
- driver: remove dead runtime->dma_bytes assignment in open() for
  managed-buffer path.

[4] https://lore.kernel.org/all/20260610-silver-pelican-of-agility-86fcbc@quoll/
[5] https://lore.kernel.org/all/20260622-whimsical-charming-seriema-dcec81@quoll/

---
Ajay Kumar Nandam (3):
      dt-bindings: sound: qcom,q6apm-dai: add stage-2 (SCM/VMID) access model
      ASoC: qcom: q6apm-dai: add VMID-based SCM assignment for mDSP buffers
      ASoC: qcom: qdsp6: generalize GPR service domain

 .../devicetree/bindings/sound/qcom,q6apm-dai.yaml  |  72 +++-
 sound/soc/qcom/Kconfig                             |   1 +
 sound/soc/qcom/qdsp6/audioreach.c                  |  12 +-
 sound/soc/qcom/qdsp6/audioreach.h                  |  22 +-
 sound/soc/qcom/qdsp6/q6apm-dai.c                   | 373 +++++++++++++++++++--
 sound/soc/qcom/qdsp6/q6apm.c                       |   8 +-
 sound/soc/qcom/qdsp6/q6apm.h                       |   2 +-
 sound/soc/qcom/qdsp6/q6prm.c                       |   2 +
 8 files changed, 455 insertions(+), 37 deletions(-)
---
base-commit: 3d5670d672ae08b8c534b7beed6f57c8b44e7b43
change-id: 20260825-a2a-shikra-vmid-v5-4975625a554a

Best regards,
--  
Ajay Kumar Nandam <ajay.nandam@xxxxxxxxxxxxxxxx>