On Thursday 17 May 2007, Laurent Pinchart wrote: > Shouldn't we implement scatter-gather for EHCI (and possibly other) > controllers ?
If by "scatter-gather" you mean "struct scatterlist", we've had that support for some time now ... in usb_sg_*() routines. That's the usual definition inside Linux. But I suspect you mean something else, not well defined. A few things I've heard called "scatter gather" in the past: - Single copy I/O to buffers specified by kernel (or user) virtual addresses. If the page boundaries are transfer buffer boundaries, that's handled already ... given a bit of glue code to pin the pages and dma-map them, and the same I/O queue mechanisms used by usb_sg_*(). - Combining N buffers, which aren't aligned on wMaxPacketSize boundaries ... e.g. buffers of 10, 500, and 2 bytes combined into one 512 byte transfer. This violates the fundamental model of what an URB signifies, so it wouldn't be at easy. So for most definitions we *do* already handle scatter/gather. - Dave ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
