Hello, we are currently in the process of getting CE certification for our embedded Linux products. Our device (under test) is configured as an ethernet gadget. We failed one test because the host machine was having problems with strange USB device behaviour.
For the test, a Linux 2.6.15 Ubuntu host machine is connected to the "device under test" via a USB A-B cable. During this particular test, a voltage pulse was sent about three times per second for 60seconds into the device's power supply. This caused a corresponding disturbance on the USB device signals. From the point of view of the host, the device under test was being disconnected and reconnected about 3 times per second (the DHCP server logs on the device were amusing). Within about 10 seconds of this pulsing, the host would no longer enumerated the device. The only way to recover was to either: a) physically reconnect the USB cable, or b) rmmod and modprobe ohci_hcd. At no point did our device fail, the problem was with the host. This is considered a "fail" because human intervention was required to recover the device to normal operation. I tried to explain that it was a problem with the host machine, but the tests have to be absolutely conclusive the device is not failing and continues to function. Since I had to act quickly to keep the tests running, I made a udev change which reloaded the ohci_hcd driver each time the USB network device was disconnected. This worked for most tests, but some more intensive tests still caused the device to fail. Eventually we had to run 6 lots of 10 second tests instead of one 60second test. My question is this: * Is there something in the USB host management code that ignores a USB device which is acting strangely? I can understand if a USB device appears and disappears three times a second it could be considered a source of noise ... * Is there anything I can do in software on the device to help survive these sorts of circumstances in the future? regards, Aras Vaichas ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
