The MM writeback status register is located after the last entry of the (H2C or C2H) descriptor.
| Bit | Bit Width | Field Name | Description |
|---|---|---|---|
| [63:48] | 16 | reserved | Reserved |
| [47:32] | 16 | pidx | Producer Index at time of writeback |
| [31:16] | 16 | cidx | Consumer Index |
| [15:2] | 14 | reserved | Reserved |
| [1:0] | 2 | err |
Error bit 1: Descriptor fetch error bit 0: DMA error |