Visible to Intel only — GUID: aci1659542942855
Ixiasoft
Visible to Intel only — GUID: aci1659542942855
Ixiasoft
5.3. DMA Descriptor Queue
The DMA contains a single descriptor FIFO for enqueuing inference requests. Descriptors potentially require multiple register writes and are added to the queue upon writing to the desc_input_output_base_addr register.
The desc_cfg_filter_base_addr and desc_cfg_num_words are registers that hold their value.
If you already enqueued a DMA descriptor and want to enqueue another descriptor with the same values for the desc_cfg_filter_base_addr and desc_cfg_num_words registers, then write to the desc_input_output_base_addr register.
If you want to change the desc_cfg_filter_base_addr and desc_cfg_num_words registers for the next descriptor, then you must set new values before writing to the desc_input_output_base_addr register.
Register |
Offset |
Attribute |
Description |
---|---|---|---|
desc_cfg_filter_base_addr |
0x000 |
RW |
Base address pointer for the configuration buffer and for the filter buffer. The filters are located at desc_cfg_filter_base_addr + desc_cfg_num_words, which is encoded in the address provided to the filter reader as configuration data. Must be aligned to a multiple of the DDR word size. |
desc_cfg_num_words - 2 |
0x004 |
RW |
Length of the configuration buffer - 2, in config words (64 bits – 32 for instruction, 32 for data) |
desc_input_output_base_addr |
0x008 |
RW |
Base address pointer for the input feature data to be used for inference, and also the base address to place the output inference results into. Must be aligned to a multiple of the DDR word size. Writing to this register enqueues a descriptor into the internal DMA descriptor queue. |
desc_diagnostics | 0x00C |
RO |
This register is useful for debugging. Production software should not need to read from this. Bit 0: Asserts if the descriptor queue overflows; this is a sticky bit which only clears after reset. Bit 1: Descriptor queue is full or almost full. Bit 2: Asserts if the inference limit for an unlicensed IP is reached. When asserted, inference requests are rejected. All other bits are reserved. |