Dear all,
this weekend I encountered a problem with libftdi when opening multiple devices
in a multithreaded application.
The programme has one thread that periodically checks if new devices have been
connected. It does this by iterating over the list returned by
ftdi_usb_find_all with proper VID and PID.
When the first device is found, a new thread (thread A) is created and the
device is opened with ftdi_usb_open_desc(handle, VID, PID, NULL, serial). Each
of the devices has a unique serial number.
When the second device if found, a new thread is created (thread B) and
ftdi_usb_open_desc fails with error code -9 (get serial number failed). I
suspect this is a permission issue since the device that comes first in the
list has already been opened by thread A - multiple open of the same device is
a problem). The device now owned by thread A is opened again by thread B - this
fails and the error code is generated.
I have changed the ftdi_usb_open_desc code to continue processing the list of
devices in this case to iterate to the device with the serial number that I
actually wanted to open. With this patch applied I can use multiple devices in
my application.
Patch against git head attached.
Kind regards,
Rolf
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libftdi-0.2-multi-open-desc.patch
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