From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2b) Gecko/20021016 Description of problem: The driver for serial ports attached to the USB port (PL2303/usbserial) does not support the complete port interface. From a practical point of view: - setserial commands does not work at all - If external equipment drops DSR and/or DCD no signals are sent to process which has the port open. - If a process opens the port, there is no (?) way to keep DTR high when the port is closed (i.e. when a chat script is complete and the control is transferred to pppd) Note: DTR *is* raised when the port is opened, so there is some hope... - It is unclear whether RTS/CTS flow control works which makes it necessary to use xon/xoff, which is a Bad Thing. Version-Release number of selected component (if applicable): kernel version 2.4.18-17.7.x How reproducible: Always Steps to Reproduce/Actual Results/Expected Results: Well, what could I say :-) Additional info: Hardware:Dell Latitude LS, Aten UC 232A This is a typical laptop problem, larger machines have "normal" serial ports.
Digging around this, the picture gets more complicated. However, one thing is sure: kermit never "sees" the CD (carrier detect) signal; it refuses to connect saying there is no carrier even if it's there. And if it can't detect the CD, of course the driver can't signal if the carrier drops. I think kermit is a pretty good way to exercise the stty interface Changing summary to reflect this. New status: - I'm still uncertain about the DTR handling; however, using stty it seems to do the Right Thing. - I havn't really tested the RTS/CTS handling, cant really say there is a bug, just this feeling. RTS is asserted correctly, though. - DCD is definitely a bug. - Setserial is really a separate issue, I'll file a new bug for this
This is pretty much a Wontfix material, I'm sorry to say. The usbserial is a mess, and pl2303 is worse. One side note is that DTR is not supposed to stay up across close (if the last process was gone), not even with clocal. Otherwise, how are you going to reset modems? The rest is a bunch of plain bugs. Currently, USB adapters are useful to connect Palm organizers only.
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