On Wed, 27 Jun 2007, Mike Nuss wrote: > It's been a while since I've written about this issue. We were able to > sidestep it for our purposes by slightly modifying the OHCI driver to > check a "force_unlinks" flag during finish_unlinks. > > We set that flag when we detect that one of our devices seems to have > not sent any data for the past 30 seconds (on the device side, they send > keepalive packets at least that often now), then our device driver sets > the force_unlinks flag and sends a command to the device to reset > itself. The device goes away, but instead of hanging, the OHCI > code sees that the flag is set, and assumes that the TD it's waiting for > is never going to show up on the donelist, so it just frees it and goes > on. Then the device finishes resetting and comes back. > > Obviously this isn't a general purpose fix, but it hasn't caused any > problems for us over the past few months. However, I seem to have found > a way to reproduce the issue more reliably, so I'm still interested in > trying to find the source of the problem. Which structures would you > like me to dump? If I dump just the affected read endpoint, here's the > output: > > ohci_hcd 0000:00:13.0: read endpoint, ed c2d912c0 state 0x0 type intr; > next ed 00000000 > ohci_hcd 0000:00:13.0: info 08405110 MAX=64 DQ SKIP EP=2-IN DEV=16 > ohci_hcd 0000:00:13.0: tds: head 02ba7300 DATA0 tail 02ba7300 > ohci_hcd 0000:00:13.0: -> td c2ba7340; urb c272ca40 index 0; hw next > td 00000000 > ohci_hcd 0000:00:13.0: info 02140000 CC=0 DATA0 DI=0 IN R > ohci_hcd 0000:00:13.0: cbp 02dbe37a be 02dbe39f (len 38) > > It seems suspicious to me that hwNextTD is null. > > Let me know what else I can provide.
I don't have time to look at this now, but I'll get back to you next week. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
