Re: Advice needed concerning ISOC transactions for a webcam
Alan Stern <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
hOn Sun, 7 Oct 2007, Ilyes Gouta wrote: > Hi! > > I'm writing a driver for a webcam for Linux. The cam is based on ALi's > M5602 USB bridge and I pretty much got it almost working since I'm > able to get the raw bayer data from it. > > I'm however facing a strange behaviour since sometimes the cam seems > stuck (after getting it correctly initialized and all) and doesn't > want to exchange ISOCs packets. Can you be more precise? What exactly goes wrong? More background would help. Is the camera a full-speed or high-speed device? What is the Iso polling interval? Which host controller driver are you using? What does the debugging log show? > Unloading the driver and reinserting > it repeatedly (without recompilation) , fixes the issue, i.e I get the > ISOCs packets flowing again between the host and the webcam. > > The other day, I added a added a couple of printk in my > isoc_urb_complete handler and got my driver working again, not all the > time but it was better than without them. So this suggested to me that > the host is kind of faster than the webcam (???) and which expects > ISOCs to be resubmited in a slower pace or something. > > I'd really want to know if some body came across such a situation and > if it really make sense to slowdown ISOC URBs re-submission. Is it > possible that ALi's M5602 USB bridge is kind of faulty and is causing > these troubles? It seems unlikely. Historically the Iso support has been the weakest part of Linux's IP stack; you may be encountering some of those problems. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel