dt-bindings: dma/net: qcom,bam: Add optional qcom,vmid property #1397
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dt-bindings: dma/net: qcom,bam: Add optional qcom,vmid property #1397quic-vishsant wants to merge 2 commits into
quic-vishsant wants to merge 2 commits into
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On platforms where a remotely-powered BAM enforces XPU access control (e.g. Qualcomm Shikra SoC with the mDSP processor), both the BAM DMA descriptor FIFOs and the BAM-DMUX RX data buffers must be SCM-assigned to the remote VMID before the first DMA transfer. Add qcom,vmid to both binding schemas to document this optional property. - qcom,bam-dma.yaml: grants remote VMID access to per-channel descriptor FIFOs via SCM assignment in bam_alloc_chan(). - qcom,bam-dmux.yaml: grants remote VMID access to the coherent RX buffer block via SCM assignment at probe time. Signed-off-by: Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
On Qualcomm Shikra SoC the mDSP(VMID 43) is the AXI master for BAM-DMUX RX data buffers and BAM descriptor FIFO accesses. The XPU enforces per-region access control; without SCM assignment granting VMID 43 access, the first DMA transfer triggers an XPU violation. Add qcom,vmid = <QCOM_SCM_VMID_NAV> to the bam-dmux consumer node so the driver SCM-assigns the coherent RX buffer block at probe; and to the bam_dmux_dma controller node so bam_dma.c SCM-assigns each channel descriptor FIFO at allocation. Only this modem-interfacing BAM path requires the assignment. Other BAM instances on Shikra (USB, crypto) are not accessible to the NAV VMID and are unaffected. Signed-off-by: Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
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On Qualcomm Shikra the mDSP (VMID 43 / QCOM_SCM_VMID_NAV) is the AXI master for BAM-DMUX RX data buffers and BAM descriptor FIFOs. The XPU enforces per-region access control; without an SCM assignment granting VMID 43 read/write access, the first DMA transfer triggers an XPU violation fault.
Document the optional qcom,vmid property in both the qcom,bam-dma and qcom,bam-dmux binding schemas, then wire it up in the Shikra DTS: