generic device DMA implementation
I'm all in favor of making the driver model support dma mapping, so usb won't need to try any more. I'd expect that to make some dma model issues for the sa1100 and uml usb ports vanish, and ideally to eliminate some code now in usbcore.
Quoted 3 lines
empty before adding new requests. I think that the Linux OHCI controller currently only queues one request per bulk or control endpoint, so I don't think it uses this feature, if it were to, it
In 2.5, all hcds are supposed to queue all kinds of usb requests, including ohci. (The ohci driver has supported that feature as long as I recall.) Storage is using that by default now, which lets high speed disks talk using big scatterlist dma requests.
That's a big change from 2.4, where queueing mostly worked but wasn't really used by many drivers. In particular, storage rarely queued more than one page ... now I've seen it queueing several dozen pages, so faster devices can reach their peak transfer speeds. (Tens of MByte/sec, sure.)
- Dave