After detaching kernel driver, the next read operation may fail

[Lekensteyn]

When lglaf.py is used for the first time on Linux, it may detach kernel drivers such as cdc_acm. After this, there is somehow a race condition which could result in a timeout during the first read. Subsequent attempts seem to work fine though.

Maybe adding time.sleep(.1) could help (haven't tried it though), but the source of the issue is unknown.

[shinobisoft]

This is exactly the issue I emailed you about a few days ago. I remedied the situation in my application by resetting the device after opening it. Since I'm using Java the language is a little different but it can easily be ported to python.

My fix: LibUsb.resetDevice( DeviceHandle );

Also, since my LgLaf is written in Java, I'm guessing anyway, I have to reset the device immediately after reading a response otherwise the next command gets sent but reading the response times out, usually with error 0x80000017.