On Mon, 10 May 2004, Andreas Hocevar wrote: > On Friday, May 07 2004, Alan Stern wrote: > > On Thu, 6 May 2004, Andreas Hocevar wrote: > > > > > Might this be a side-effect of the new routines checking for the "00 00 00 > > > ..." packets that the genesys chip produces? When using verbose mode in > > > cdrdao the cue-sheet is printed to the console, and it contains a lot of "00 > > > 00 00 ...". > > > > What new routines are you talking about? > > I'm referring to the following section of Changelog-2.6.4 (without > having looked those routines up in the source code -- shame on me): > > --- begin Changelog-2.6.4 --- > [PATCH] USB Storage: Handle excess 0-length data packets > > This patch is an attempt to cope with Genesys Logic's, shall we say, > creative approach to implementing the USB protocols. Their high-speed > mass storage devices sometimes add an excess 0-length packet to the end of > a data phase transmission. Of course we don't read that packet as part of > the data phase; we see it as a 0-length CSW message. The real CSW follows > immediately after. (Or sometimes a STALL follows immediately after, with > the real CSW coming after that!) > > The patch checks the results of the first attempt to read the CSW. If it > sees a normal packet (not a STALL) with length 0, it retries the read. > Reports from two users indicate that it improves the performance of their > USB-2 DVD drives. > --- end Ehangelog-2.6.4 ---
That change doesn't do what you seem to think. It doesn't look for packets containing patterns of 0's; rather it looks for packets having length 0. > I will switch back to 2.6.3 and check again, but AFAIR it worked with > 2.6.3. > > > So far as I can tell, no amount of additional debugging information will > > help fix the Genesys problem. What we need is expert advice from a > > technical person who understands how the chip works. > > I tried to get in touch with them several months ago, but got no answer > (of course?). I think the best thing we can do is advice linux users not > to use enclosures with genesys chipset, until they give us enough > information to understand all facettes of their "creative approach" to > ehci implementation. At this point it seems fair to put up a warning on the linux-usb web site about problems in trying to use Genesys interfaces at high speed. Maybe also on the equipment-compatibility listing sites. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by Sleepycat Software Learn developer strategies Cisco, Motorola, Ericsson & Lucent use to deliver higher performing products faster, at low TCO. http://www.sleepycat.com/telcomwpreg.php?From=osdnemail3 _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
