On Fri, Jan 30, 2009 at 12:14:11PM +0100, Oliver Neukum wrote: > Am Thursday 29 January 2009 17:30:27 schrieb David Vrabel: > > Alan Stern wrote: > > > > > > Pushing scatterlists down to the HCD level would involve several > > > nontrivial changes to the code. The issue of the buffer lengths is > > > just one of them, although it is perhaps the most vexing. > > > > I don't see where the complexity is. The HCD simply fills the > > hardware's s-g list structures based on the s-g list in the URB. > > > > Obviously, none of the existing HCDs can support s-g lists in this > > manner and should continue to only accept URBs without s-g lists. > > Meaning that drivers that want to take advantage of this would need > to test for this ability and have different code paths for it. I don't think drivers need to change. The USB core's sg_init and sg_wait function behaviors would change, but their API would not. Where do you see the need for drivers to change? > Therefore I would prefer chained URBs despite their size. For HCDs > whose maximum chain length is exceeded usbcore could walk the chain > and submit them iteratively. What do you mean by "chain length"? Something to do with URB anchors? Sarah -- 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
