Thumbs up to the ZyDAS engineers, who have been responsive via email.

I asked them about the problem which many of us have seen using ZD1211 on Linux, where after some unspecified amount of time, the device stops working, and the kernel logs suggest the device has been disconnected. Unplugging and replugging the device is enough to get things working again.

I have seen this once myself (with zd1211rw), however I am not 100% sure it was the same thing, since I don't trust the USB extension cable that I am using.

ZyDAS informed me that they suspect at least one of the causes for the bug is reading the contents of /proc/bus/usb/devices (or running lsusb, or running any other program which lists the devices attached to your USB bus) during network transfer.

Firstly, I'm looking for information from people who have seen this bug (the disconnections) with either driver with any form of regularity. If you are one of these people, please reply to this mail, telling me:

 - How often you see these (days, weeks, months apart?)
 - Which kernel version you use and have been using recently

Secondly, I'm looking for people to see if they can reproduce this problem, regardless of whether they have seen it before or not. To do this:

1. Connect to your network using ZD1211
2. Generate as much network traffic as possible, i.e. start downloading a large file from a local machine, or upload one, or even do both at the same time
3. Run "cat /proc/bus/usb/devices"
4. If this doesn't cause immediate disconnect, repeat step 3 many times (say up to 100?) in quick succession. Try and break the poor thing.
5. Let me know how you get on (either outcome)

If anyone can reproduce this relatively easily, we can patch the Linux kernel with a workaround for these devices.


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