Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 11/27/2024
Public
Document Table of Contents

5.4.6.3.4. DMA Errors

The host controller has the following protection mechanisms on the DMA/manager interface:

  • Descriptor validation: This mechanism comes with the SD host controller standard. The scatter-gather DMA checks whether the valid attribute is set 1 in the read descriptors. This mechanism is applicable for all variants of the descriptors including ADMA2 (SD) and command queuing (eMMC). If the valid attribute is 0, the DMA stops transfer and reports DMA error.
  • AXI/AHB transaction error detection: This mechanism enables the DMA to stop any pending transfers and to report the DMA/manager interface error to system via status registers. The DMA does not send new requests, completes all already requested/queued transactions, and stops when all transactions are finished without violating a bus protocol. In addition, in case of read transaction, read data is altered with 0x00 which in consequence protects scatter-gather DMA from interpreting potentially random data as a descriptor. On the bus transaction error, the host controller reports AXI Error (HRS03[3:0]) and might report DMA Error (SRS12[25]).