On Thu, 21 Dec 2006, Z F wrote: > Hello Alan, > > I finally was able to run usbmon on this camera (the file is attached) > In USB1 mode, the communication with the camera works perfectly, > but in the USB2 mode, there is a huge number of errors. > > I was wondering if you could take a look at the log file and see > if you can find any hints of why the errors and usb resets might be > happening. I agree with you that cabling might be a problem and > it is very hard to diagnose such problems. I can only say that I > attached two other usb2 devices to the same USB port > and both of them work good where as the camera does not.
I looked at it. As near as I can tell, this is an intermittent low-level hardware problem -- in other words, something interfering with the transmissions along the USB cable. > Also, I have tested the camera on a different linux system and it > works good in USB2 mode. So I start to suspect the USB controller > issues. The different controllers are: > > Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2 EHCI ----- works > > ALi Corporation USB 2.0 Controller. --- does not The logs don't indicate a controller problem. It's worth noting, however, that Intel hardware generally tends to be very high quality overall whereas ALi is often not quite as good. > Maybe I should give some options to the usb modules? There are no suitable options to give. > I have tried setting log2_irq_thresh option of the ehci module to some > non-zero value, but that did not change the behavior. > I have tried on the 2.6.16.1 kernel (which I am running) and on > 2.6.19.1 which I just downloaded today for testing with the same > results. Sometimes hardware problems like this aren't caused by a failure in any one part but by an overall incompatibility. For example: I have a USB hard disk drive enclosure which doesn't work on my home computer. The same cable and enclosure _do_ work on my office computer. On the other hand, if I use a different cable then the enclosure _does_ work at home. And if I keep the old cable attached to the home computer but attach a USB flash drive instead of the hard drive enclosure, then again it works. Thus replacing any one of the components (computer, cable, enclosure) fixes the problem. So which component is at fault? 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 _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
