GRXFIFOPRIHST (USB3_XHCI) Register Description
| Register Name | GRXFIFOPRIHST |
|---|---|
| Offset Address | 0x000000C61C |
| Absolute Address |
0x00FE20C61C (USB3_0_XHCI) 0x00FE30C61C (USB3_1_XHCI) |
| Width | 32 |
| Type | mixedMixed types. See bit-field details. |
| Reset Value | 0x00000000 |
| Description | Global Host RX FIFO DMA Priority Register This register specifies the relative DMA priority level among the Host RXFIFOs (one per USB bus instance) within the associated speed group (SS or HS/FSLS). Each register bit[n] controls the priority (1: high, 0: low) of RXFIFO[n] within a speed group. When multiple RXFIFOs compete for DMA service at a given time (i.e., multiple RXQs contain RX DMA requests and their corresponding RXFIFOs have data available), the RX DMA arbiter grants access on a packet-basis in the following manner: - 1. Among the FIFOs in the same speed group (SS or HS/FSLS): a. High-priority RXFIFOs are granted access using round-robin arbitration b. Low-priority RXFIFOs are granted access using round-robin arbitration only after high-priority RXFIFOs have no further processing to do (that is, either the RXQs are empty or the corresponding RXFIFOs do not have the required data). - 2. The RX DMA arbiter prioritizes the SS speed group or HS/FSLS speed group according to the ratio programmed in the GDMAHLRATIO register. For scatter-gather packets, the arbiter grants successive DMA requests to the same FIFO until the entire packet is completed. This register is present only when the core is configured to operate in the host mode (includes DRD and OTG modes). The register size corresponds to the number of configured USB bus instances; for example, in the default configuration, there are 3 USB bus instances (1 SS, 1 HS, and 1 FSLS). |
GRXFIFOPRIHST (USB3_XHCI) Register Bit-Field Summary
| Field Name | Bits | Type | Reset Value | Description |
|---|---|---|---|---|
| Reserved | 31:3 | roRead-only | 0x0 | Reserved |
| grxfifoprihst | 2:0 | rwNormal read/write | 0 | Host RxFIFO priority |