"Tosoni" <[EMAIL PROTECTED]> writes: >> OTOH I wonder what does the device in question require WRT the >> serial port and WRT RTS line in particular. >> I know there are some half-duplex converters which drive RTS only >> while sending and which require CTS to send. > > As far as I know in the old times this was the *standard* way to use a modem > (per CCITT V24), and even nowadays many modems can handle this method for > transmit, to stay compatible with the standard.
I think it wasn't standard for real modems as they were full-duplex (even these 1200/75 or what was that) but it was for other devices such as current loops (which were frequently half-duplex). I've seen such devices quite recently, perhaps ~ 10 years ago. OTOH I think even "current" PC BIOSes use such signaling. > Think of radio modems. Some are inherently half duplex. Sure. But /dev/ttyS* ports are full-duplex, with CRTSCTS or without, so they don't use such handshaking. >> They are perhaps a bit broken <snip> > No, no, they apply an old standard. Probably they are old as well. I was thinking of a particular piece of hardware and it was definitely broken a bit. "Selective compliance", maybe. > It's a pity that Linux (or Unixes) never handled RTS this way. > I feel that the /proc or sysfs solutions are the best to alter this well > established default in this driver. It would not break existing installed > hardware. /proc is probably no-no. For such signaling, it would perhaps be better to invent another flag, similar to CRTSCTS. The driver would, of course, need some real code for that. -- Krzysztof Halasa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
