The resource-allocation routines provide the driver with several options when handling allocation failures. The waitfp argument indicates whether the allocation routines will block, return immediately, or schedule a callback, as shown in Table 7-1.
Table 7-1 Resource Allocation Handling
waitfp |
Indicated Action |
---|---|
DDI_DMA_DONTWAIT |
Driver does not need to wait for resources to become available. |
DDI_DMA_SLEEP |
Driver is willing to wait indefinitely for resources to become available. |
Other values |
The address of a function to be called when resources are likely to be available. |