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1. Terms and Acronyms
2. Introduction
3. Functional Description
4. Interface Overview
5. Parameters (H-Tile)
6. Parameters (P-Tile and F-Tile)
7. Designing with the IP Core
8. Software Programming Model
9. Registers
10. Troubleshooting/Debugging
11. Multi Channel DMA Intel FPGA IP for PCI Express User Guide Archives
12. Revision History for Multi Channel DMA Intel FPGA IP for PCI Express User Guide
4.1. Port List
4.2. Clocks
4.3. Resets
4.4. Multi Channel DMA
4.5. Bursting Avalon-MM Master (BAM) Interface
4.6. Bursting Avalon-MM Slave (BAS) Interface
4.7. Config Slave Interface (RP only)
4.8. Hard IP Reconfiguration Interface
4.9. Config TL Interface
4.10. Configuration Intercept Interface (EP Only)
4.11. User Functional Level Reset (FLR)
4.12. User Event MSI-X Request Interface
8.1.6.1. ifc_api_start
8.1.6.2. ifc_mcdma_port_by_name
8.1.6.3. ifc_qdma_device_get
8.1.6.4. ifc_num_channels_get
8.1.6.5. ifc_qdma_channel_get
8.1.6.6. ifc_qdma_acquire_channels
8.1.6.7. ifc_qdma_release_all_channels
8.1.6.8. ifc_qdma_device_put
8.1.6.9. ifc_qdma_channel_put
8.1.6.10. ifc_qdma_completion_poll
8.1.6.11. ifc_qdma_request_start
8.1.6.12. ifc_qdma_request_prepare
8.1.6.13. ifc_qdma_descq_queue_batch_load
8.1.6.14. ifc_qdma_request_submit
8.1.6.15. ifc_qdma_pio_read32
8.1.6.16. ifc_qdma_pio_write32
8.1.6.17. ifc_qdma_pio_read64
8.1.6.18. ifc_qdma_pio_write64
8.1.6.19. ifc_qdma_pio_read128
8.1.6.20. ifc_qdma_pio_write128
8.1.6.21. ifc_qdma_pio_read256
8.1.6.22. ifc_qdma_pio_write256
8.1.6.23. ifc_request_malloc
8.1.6.24. ifc_request_free
8.1.6.25. ifc_app_stop
8.1.6.26. ifc_qdma_poll_init
8.1.6.27. ifc_qdma_poll_add
8.1.6.28. ifc_qdma_poll_wait
8.1.6.29. ifc_mcdma_port_by_name
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8.3.3.3. Completions Management
Kernel module supports two modes of descriptor process completion indication . This is in accordance with the support of the hardware.
- For both of these modes eventfds are used to pass the completed request counter to the application from the driver
- The eventfds are passed from the user application to kernel driver using a control message
- A control message: It is a structure that contains the details of the eventfds, file size (#descriptors per file) and payload size per queue
- It is passed by the user application before starting of transfer using the read/write system call
- In order to differentiate between control message & a DMA request, the size must be set to zero in the read/write system call argument to indicate the former
- The application uses a read operation on the eventfd to acquire the count of completed requests.
Figure 43. Completion Management Flow
In both modes:
- Updation of the context of the associated descriptor queue also increases the 64 bit counter of the eventfd of the application associated with the queue
- The application uses read operation on the eventfd to receive the recent number of completed requests
In Interrupt Mode:
- Upon completion of request the MCDMA IP generates MSI-X signals
- This interrupt signal invokes the interrupt handler of the driver
- In the above diagram, steps 1 and 2 of interrupt mode occur asynchronously
In Poll Mode:
- Application uses poll file operation to poll a channel
- ifc_device_poll function of kernel driver polls both the queues of the channel and returns flags POLLIN,POLLOUT and/or POLLRDNORM, POLLWRNORM depending on the status of the queues