Re: [PATCH v6 0/6] PCI: endpoint: Expose endpoint DMA resources (part 2/3)

[Frank Li]

On Tue, Aug 04, 2026 at 12:38:49PM +0900, Koichiro Den wrote:
> Hi,
>
> This is v6, part 2 of three series for PCI endpoint DMA.
>
> The three series are:
>
>   * part 1: dmaengine: dw-edma: Prepare for PCI EP DMA
>   * part 2: PCI: endpoint: Expose endpoint DMA resources
>   * part 3: PCI: endpoint: Add PCI DMA endpoint function

This part only 3 patch, You can merge to part2. It will be easy to know
overall picture.

Frank
>
> This series defines the endpoint DMA BAR metadata and auxiliary
> resources, adds EPC operations for DMA channel delegation, and teaches
> the DesignWare endpoint controller to publish and delegate its
> integrated DMA resources.
>
> The metadata lives in a normal endpoint BAR, not in PCI config space.
> This keeps discovery independent from controller-specific writable
> extended capability storage.
>
> Part 1 v6 has landed in linux-next via dmaengine/next:
> https://lore.kernel.org/all/20260721062815.4117887-1-den@xxxxxxxxxxxxx/
>
> v6 is rebased on next-20260803.
>
> Best regards,
> Koichiro
> ---
> Changes in v6:
>   - Rebase onto next-20260803, which includes part 1 v6.
>   - Use one DMA resource snapshot for bounds checking and array filling.
>     (Sashiko)
>   - Move DMA resource exposure after delegation support so every advertised
>     channel is immediately usable. (Sashiko)
>
> Changes in v5:
>   - Keep reporting a standalone doorbell when linked-list DMA resources
>     are unavailable. (Sashiko)
>   - Serialize irq_mode restoration with channel state updates. (Sashiko)
>   - Clarify the provider-defined sharing-group quiesce contract.
>   - Use guard()/scoped_guard() for new code.
>
> Changes in v4:
>   - Rebased onto the new part 1 series.
>   - "dmaengine: dw-edma: Add delegated channel request helpers" moved
>     from part 1 into this series, next to its only users; this also
>     resolves the undeclared-functions issue reported against v3 5/5.
>     (Sashiko)
>   - Lift the v3 PF0-only restriction on DMA resource exposure and
>     channel delegation: part 1 now programs the per-channel requester
>     function number. Delegation to PF1+ therefore requires part 1
>     applied on the host side.
>   - Move pci_epc_function_is_valid() up to avoid a potential error
>     pointer dereference. (Sashiko)
>
> Changes in v3:
>   - Decouple logical DMA channel metadata from descriptor memory resources.
>     Logical channels now refer to descriptor memory by resource ID instead
>     of embedding descriptor metadata in each channel resource. (Sashiko)
>   - Replace the v2 DMAengine filter-callback metadata with EPC-level DMA
>     channel delegation/reclaim operations, keeping DMAengine provider
>     details out of generic EPC resource metadata.
>   - Add the DesignWare EPC backend for DMA channel delegation.
>   - Limit DesignWare endpoint DMA resource exposure to linked-list channels
>     until non-LL metadata and host-side parsing are added.
>   - Suppress DesignWare DMA auxiliary resources when the local DW eDMA
>     provider is not available.
>   - Reject VF DMA resource and delegation requests because the DWC
>     eDMA/HDMA register window exposed to the Root Complex is PF-only.
>
> Changes in v2:
>   - Follow the part 1/3 v2 channel-claim model: EPC DMA resources now
>     carry DMAengine filter information instead of raw DMA channel
>     pointers. (Sashiko)
>   - Update the DesignWare endpoint resource provider accordingly. (Sashiko)
>
> v5: https://lore.kernel.org/r/20260717050635.2145014-1-den@xxxxxxxxxxxxx/
> v4: https://lore.kernel.org/r/20260710082156.2395844-1-den@xxxxxxxxxxxxx/
> v3: https://lore.kernel.org/r/20260620170438.3756593-1-den@xxxxxxxxxxxxx/
> v2: https://lore.kernel.org/r/20260525063129.3316894-1-den@xxxxxxxxxxxxx/
> v1: https://lore.kernel.org/r/20260521063405.2842644-1-den@xxxxxxxxxxxxx/
>
>
> Koichiro Den (6):
>   PCI: endpoint: Define endpoint DMA BAR metadata format
>   PCI: endpoint: Add DMA auxiliary resource metadata
>   PCI: endpoint: Add API to delegate EPC DMA channels to the host
>   dmaengine: dw-edma: Add delegated channel request helpers
>   PCI: dwc: Implement endpoint DMA channel delegation
>   PCI: dwc: Expose endpoint DMA resources
>
>  MAINTAINERS                                   |   1 +
>  drivers/dma/dw-edma/dw-edma-core.c            |  91 ++++++++
>  .../pci/controller/dwc/pcie-designware-ep.c   | 205 +++++++++++++++++-
>  drivers/pci/endpoint/pci-epc-core.c           | 105 +++++++++
>  include/linux/dma/edma.h                      |  14 ++
>  include/linux/pci-ep-dma.h                    | 170 +++++++++++++++
>  include/linux/pci-epc.h                       |  62 ++++++
>  7 files changed, 640 insertions(+), 8 deletions(-)
>  create mode 100644 include/linux/pci-ep-dma.h
>
> base-commit: 9a4cdc958dd79fc6c3b20b51a10debec6ca09fec
> --
> 2.51.0
>