On Tue, Apr 20, 2004, David Brownell <[EMAIL PROTECTED]> wrote: > Johannes Erdfelt wrote: > > > >Be careful. You can't modify certain values of the QH while it's on the > >schedule safely. ... > > But it's possible to use the "dummy TD" approach even with UHCI; > just leave the last TD disabled until you need to fill it out as > the first TD for a new URB. No need to write the QH, just TDs.
It's dangerous to do so. The status/control fields of the TD are R/W by the HC and if it's in the schedule, you have to assume that the HC is writing to those fields, even if the TD is not active. Atleast, that is the behaviour I saw when I tried doing something similar a long time and it agrees with the specs AFAICT. However, using a QH per URB does work and isn't that much more complicated. JE ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
