Hi all,
I have a USB based serial port device (/dev/ttySxx) which does not work when
beeing used with cygwin programs (e.g. getty or even python).
It seems this is because the baudrate is initially zero after the device
has been created:
$ /cygdrive/c/Windows/System32/mode.com COM72
Status von Gerät COM72:
-----------------------
Baudrate: 0
Parität: None
Datenbits: 0
Stoppbits: 1
Timeout: OFF
XON/XOFF: OFF
CTS-Handshaking: OFF
DSR-Handshaking: OFF
DSR-Prüfung: OFF
DTR-Signal: OFF
RTS-Signal: ON
This makes tcgetattr fail when beeing used on this device.
119 117652 [main] stty 2325 fcntl: 0 = fcntl(0, 4, 0x10000)
732 118384 [main] stty 2325 fhandler_serial::tcgetattr: Invalid baud rate 0
111 118495 [main] stty 2325 __set_errno: virtual int
fhandler_serial::tcgetattr(termios*):1027 setting errno 22
116 118611 [main] stty 2325 tcgetattr: -1 = tcgetattr(0, 0x100419060), errno
22
I assume that allmost all programs use tcgetattr before partially changing
parameters in the struct that is returned.
I suggest not to make tcgetattr fail in this case, but return B0 instead. User
programs
will most likely change the bitrate setting anyhow.
After setting an initial baudrate with mode.com, the device works well with
cygwin.
Regards,
Stefan Althöfer
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