[PATCH v6 0/4] ASoC: qcom: enable audio on stage-2 protected DSPs (mDSP)

[Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>]

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 driver detects the mDSP target at runtime from the GPR domain_id
(GPR_DOMAIN_ID_MODEM) and enables the SCM assignment path automatically.
VMIDs are hardcoded in the driver (HLOS + MSS_MSA + LPASS) rather than
read from DT, following the consensus from v2 review discussion with
Krzysztof Kozlowski and Srinivas Kandagatla.

Tested on Qualcomm Shikra with mDSP audio playback and capture.

Prior versions:
v1 (VMID binding + driver + GPR domain):
  https://lore.kernel.org/all/20260609064038.492641-1-ajay.nandam@oss.qualcomm.com/
v1 (memory-region binding + DTS):
  https://lore.kernel.org/all/20260618113509.2025881-1-ajay.nandam@oss.qualcomm.com/
v2:
  https://lore.kernel.org/all/20260826-a2a-shikra-vmid-v5-v2-0-c3dc62354eee@oss.qualcomm.com/
v3:
  https://lore.kernel.org/all/20260918-vmid-v3-v3-0-f1cbf47bf173@oss.qualcomm.com/
v4:
  https://lore.kernel.org/all/20260922-vmid-v4-v4-0-5fe21b1365a1@oss.qualcomm.com/

Changes since v4:
- Resend — v4 was partially delivered due to SMTP failure, no code
  changes.

Changes since v3:
- Split DT binding changes into a separate patch (3/4) from the driver
  implementation (4/4). (Rob Herring)
- SCM-assign the data-path pool (memory-region[1]) as a single whole-pool
  operation at probe instead of per-stream in pcm_new()/compr_open().
- SCM-assign compressed audio stream buffers in compr_open() and
  unassign in compr_free() when no data-path pool is present. v3 only
  covered PCM streams.
- Fix error path in pcm_new: unassign SCM region if memory_map fails
  after a successful SCM assign, preventing a resource leak.
- Account for PAGE_SIZE padding in reserved-memory pool budget
  calculation. v3 under-reserved by PAGE_SIZE per stream, which could
  overflow the pool at maximum concurrent stream count.

Signed-off-by: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>
---
Changes in v6:
- Drop redundant maxItems from the qcom,q6apm-dai memory-region schema. (Rob Herring)
- Require q6apm-dai nodes to provide either iommus or memory-region. (Krzysztof Kozlowski)
- Serialize SCM region tracking with a mutex. (Mark Brown)
- Use %pa for the reserved-memory pool size diagnostic. (Mark Brown)
- Use the ASoC dt-bindings subject prefix for patch 3. (Mark Brown)
- Rebase onto v7.3-rc1.
- Validate v6 on Qualcomm Shikra with mDSP audio playback and capture.
- Link to v5: https://patch.msgid.link/20260922-vmid-v4-v5-0-e79cfd7af5b3@oss.qualcomm.com

---
Ajay Kumar Nandam (4):
      ASoC: qcom: q6apm: clear g_apm on driver removal
      ASoC: qcom: qdsp6: generalize GPR service domain
      ASoC: dt-bindings: qcom,q6apm-dai: add memory-region and relax iommus
      ASoC: qcom: q6apm-dai: add SCM buffer assignment for mDSP platforms

 .../devicetree/bindings/sound/qcom,q6apm-dai.yaml  |  17 +-
 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                   | 317 +++++++++++++++++++--
 sound/soc/qcom/qdsp6/q6apm.c                       |   9 +-
 sound/soc/qcom/qdsp6/q6apm.h                       |   2 +-
 sound/soc/qcom/qdsp6/q6prm.c                       |   2 +
 8 files changed, 348 insertions(+), 34 deletions(-)
---
base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
change-id: 20260921-vmid-v4-0116efe5937b

Best regards,
--  
Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>