On Mon, 28 Dec 2009, Sarah Sharp wrote: > In the random questions department: > > Will Linux ever schedule an active isoc TD at the end of the frame list (i.e. TD with the horizontal T-bit set) ? I'm a little confused by the question. The T bit has nothing to do with whether or not an iTD is active or is at the end of the frame list. It indicates that no other iTDs, QHs, or FSTNs follow this iTD in the current frame. Furthermore the word "active" is redundant, in the sense that Linux never puts an _inactive_ iTD on the schedule (obviously). iTDs are scheduled for all appropriate frames regardless of their position in the frame list. For example, consider what happens if an endpoint has an interval of 8 uframes. When it is in use, it needs to have an iTD scheduled in every frame -- including the frame at the end of the frame list. Are you asking whether Linux will ever add an iTD with the T bit set to the schedule? Yes, it will. When an iTD is the first item added to a frame, it is be added with the T bit set. 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
