On Sun, 29 Aug 2010, Artem Makhutov wrote: > Maybe this are the RF-interferences of the modems. That certainly is possible. Are the modems close together? > I can try to rework my "RF-shielding-case" for the usb-hubs by soldering > all remaining holes. > No, it makes no difference. I was also able to reproduce this problem with > only 3 modems directly connected to the motherboard - without add-on cards. > > Also on different computers. I wouldn't be surprised if it happened even with only 2 modems. > > That's another indication of a hardware problem. Furthermore, this > > particular error code (xacterr in the log) comes directly from the > > controller itself. It indicates that the computer failed to receive a > > packet the modem should have sent. > > > Can it be possible that the USB traffic from one modem is somehow > influencing other modems? No; only one device is allowed to transmit on the USB bus at any time, and a device listens only to packets sent by the host to the device's address. > This kind of problems were reported by a lot of different users. > As I said before I have also this kind of problems on different computers. > So I don't think that this is a problem with my cables. It's possible that somehow the problem is in the EHCI controller. But if it is, I have no idea what the cause is or how to work around it. > Usually I am loosing the connection to the modem after such a problem. > I can not send any commands to the modem any more and I also can't > receive any "updates" from the modem after such a "crash". The only > thing that I can do is replugging the modem or restarting the PC. Are you sure about that? In the log you posted there were several errors; it looked like everything kept on working okay after the first couple of them. > This did not happend on FreeBSD. All modems were fully operational the > whole time. > > Tomorrow I will do some more tests. > > During the last test all modems were idle. Only the "control connection" > was opened. Yes, that's where the errors occurred. And at least one of them occurred while there was no "control data" being sent. The host polled the endpoint to see if any data was ready and then it did not receive the "no data" signal from the modem. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
