http://bugs.winehq.org/show_bug.cgi?id=10051
--- Comment #1 from Juan Lang juan_lang@yahoo.com 2007-10-16 10:26:29 --- Created an attachment (id=8606) --> (http://bugs.winehq.org/attachment.cgi?id=8606) reg file to work around problem
The bug isn't precisely in setupapi. As I commented on bug 9902, explorer's hal.c needs to create devices for the serial port. Try adding the attached registry entries to your registry ('regedit comport.reg') and seeing if that helps. Change the SymbolicLink value to the DOS name of the COM port you actually want to use. You'll need an up to date git, too - some fixes went in post-0.9.47.