I don't know how to navigate the kernel's git tree, but I have noticed that the 1.6 version of the ftdi_sio driver included in kernel 2.6.35 always asserts/deasserts the DTR line regardless of hup setting by stty or similar. I'm fairly sure version 1.5 of the driver doesn't exhibit this behaviour but I can check for sure if you need me to. to reproduce: stty -hup < /dev/ttyUSB0 cat < /dev/ttyUSB0 what used to happen in old driver (what I want to happen): DTR does NOT assert/deassert at 2nd command start what happens: DTR asserts at 2nd command start this behaviour causes my arduino to reset every time I open the port, causing problems for some of my projects. Another clue: when I stty crtscts, the DTR line no longer toggles when I open the port, however I can't send any data as the arduino does not use rts/cts handshaking lines! If there is some other method I should use to get the behaviour I want, please inform me. I created the attached patch to get the behaviour I want. I didn't touch any of the set_mctrl calls since I'm only interested in stopping the line going low, but I'm sure some should be similarly altered for symmetry. I'm not on the mailing list so please cc me any responses.
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ftdi_sio_dtr_hup_fix.patch
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