On Mon, 25 Sep 2006, Steve Calfee wrote: > >> > This indicates that the problem is a small hardware incompatibility, > >>as I have said before. > >> > >>We attached a High Speed hub to our system and inserted this disk in the > >>hub. The device works perfectly in such mode. > > This is more than a small hardware problem. Assuming this HS hub was self > powered, it indicates either your device took too much VBUS current, your > host could not supply enough vbus power, your host transceiver has a > problem, OR you have a major fussy device in receiving data. And even with > this test info I have to assume that you used the same cable (a possible > failure) between the good hub and the root hub. > > >> > >>We also attached a Full speed hub (used in both bus and self powered > >>mode) to our system and inserted this disk in the hub. The device fails > >>to work in such mode. The reasons for device failure are identicle to > >>case when it is directly connected to our system.
Probably the high-speed hub re-buffers or re-times the signals whereas the full-speed hub doesn't. > What did your bus analyzer say in this case? Full speed is much more > forgiving than high speed. > > I have seen a high speed mass storage device which would fail during > enumeration in full speed (a small percentage of the time). HS is supposed > to fall back to FS for all usb 2.0 devices, but it does seem that > occasionally some devices are not 100% compliant :) > > > > >> > >>The above experiments do not indicate hardware incompatibility. Do you > >>agree ? > >> > > Not in my opinion, this seems likes a major hardware problem somewhere. I agree with Steve. The experiments _definitely_ indicate a hardware incompatibility. If it were a software problem then the presence or absence of intermediate hubs wouldn't make any difference. Alan Stern ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
