[PATCH 0/2] net: wwan: qcom_bam_dmux: Alloc RX buffers as a single coherent block

[Vishnu Santhosh]

On platforms where the modem DMAs into the BAM-DMUX RX data buffers and
the XPU (eXternal Protection Unit) enforces per-region access control,
each individually DMA-mapped RX buffer consumes an XPU resource group.
With only ~16 groups available on Shikra (mDSP, VMID 43 / NAV), the
per-buffer mappings exhaust the table and inbound transfers fault.

This series adds a qcom,shikra-bam-dmux compatible and have the driver
select QCOM_SCM_VMID_NAV internally via that compatible's match data.
When matched, the driver allocates all RX buffers as a single
contiguous coherent block and SCM-assigns it to HLOS plus the VMID
once at probe, consuming one XPU resource group instead of many.

Platforms that do not use the qcom,shikra-bam-dmux compatible are
unaffected: the existing per-buffer dma_map_single() path is
unchanged.

Signed-off-by: Vishnu Santhosh <vishnu.santhosh@xxxxxxxxxxxxxxxx>
---
Vishnu Santhosh (2):
      dt-bindings: net: qcom,bam-dmux: Add qcom,shikra-bam-dmux compatible
      net: wwan: qcom_bam_dmux: Alloc RX buffers as a single coherent block

 .../devicetree/bindings/net/qcom,bam-dmux.yaml     |   8 +-
 drivers/net/wwan/Kconfig                           |   1 +
 drivers/net/wwan/qcom_bam_dmux.c                   | 134 +++++++++++++++++++--
 3 files changed, 132 insertions(+), 11 deletions(-)
---
base-commit: 3b029c035b34bbc693405ddf759f0e9b920c27f1
change-id: 20260714-qcom-bam-dmux-vmid-ext-d9289db310c1

Best regards,
-- 
Vishnu Santhosh <vishnu.santhosh@xxxxxxxxxxxxxxxx>