On Wed, Apr 07, 2010 at 11:57:14AM -0400, Alan Stern wrote: > On Wed, 7 Apr 2010, Ashot Madatyan wrote: > > > Hi Alan, > > > > Please see my inlined questions/comments below. > > > I'm not sure what the spirit of the USB 3.0 spec would say, but my > > feeling is that the "extra" and "extralen" fields in usb_host_endpoint > > should encompass all the following descriptors, including the > > SuperSpeed Endpoint Companion descriptor, up to the next endpoint or > > interface. > > > > This would mean that there would be need to have a usb_host_ss_ep_comp > > structure at all. > > [Ashot S. Madatyan] > > This would mean that there would be NO need to have a usb_host_ss_ep_comp > > structure at all. > > If you meant exactly that, then I quite agree and think this is the best way to go about. > > Yes, that is what I meant. Sorry about the typo. Curtis Stevens on the USB-IF UASP mailing list said that the USB3 bus spec takes precedence, and the pipe descriptors should go after the SuperSpeed endpoint companion descriptors. It's really not that hard to parse the usb_host_endpoint extra field, and then if you don't find the pipe descriptor, parse the usb_host_ss_ep_comp extra field. ISTR David Vrabel saying there's some code in the WHCI driver to parse those extra fields to find the wireless BOS descriptor, and it should probably be moved into a general purpose function in the USB core. Maybe it could be used to get the pipe descriptors? I don't like to have the usb_host_ss_ep_comp structure go away completely, as the USB core and the xHCI driver both use it. So there needs to be easy access to the descriptor without needing to re-parse the extra field every time. You could have the extra field in usb_host_endpoint encompass all the descriptors after the endpoint (including the SuperSpeed endpoint companion descriptor), and also keep a pointer to the usb_host_ss_ep_comp in usb_host_endpoint. I would be fine with that. I really struggled with the descriptor parsing code to get it right, so I really don't ever want to touch that code again. Maybe someone else wants to take a shot at it? Sarah Sharp -- 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
