On Fri, 5 Mar 2010, Oliver Neukum wrote: > Am Freitag, 5. März 2010 21:10:17 schrieben Sie: > > This patch (as1350) removes all usages of coherent buffers for USB > > control-request setup-packet buffers. There's no good reason to > > reserve coherent memory for these things; control requests are hardly > > ever used in large quantity (the major exception is firmware > > transfers, and they aren't time-critical). Furthermore, only seven > > drivers used it. We might as well always use streaming DMA mappings > > for setup-packet buffers, and remove some extra complexity from > > usbcore. > > 1. Are you sure about speed concerning CB(I) storage devices? Modern storage devices never use CB(I); they always use Bulk-only. There can't be many CB(I) devices that even support high-speed operation -- maybe none. The CB(I) protocol is already very inefficient; adding a small extra penalty won't be noticeable. > 2. Isn't that introducing an asymmetry into the API? The asymmetry is already present in the USB protocol: Control requests are the only sort of transfer to have a Setup packet. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
