usb_ep_alloc_buffer — allocate an I/O buffer
void * usb_ep_alloc_buffer ( | struct usb_ep * | ep, |
| unsigned | len, | |
| dma_addr_t * | dma, | |
| gfp_t | gfp_flags); |
epthe endpoint associated with the buffer
lenlength of the desired buffer
dmapointer to the buffer's DMA address; must be valid
gfp_flagsGFP_* flags to use
Returns a new buffer, or null if one could not be allocated.
The buffer is suitably aligned for dma, if that endpoint uses DMA,
and the caller won't have to care about dma-inconsistency
or any hidden “bounce buffer” mechanism. No additional per-request
DMA mapping will be required for such buffers.
Free it later with usb_ep_free_buffer.
You don't need to use this call to allocate I/O buffers unless you want to make sure drivers don't incur costs for such “bounce buffer” copies or per-request DMA mappings.