Re: Re hardware handshake support for 2.0/2.2/2.4

From: Roger Gammans (
Date: Fri Aug 04 2000 - 09:20:35 EST

On Fri, Aug 04, 2000 at 02:58:25PM +0100, Alan Cox wrote:
> > Half-duplex RTS switch, tx when RTS high[1]
> > Half-duplex RTS switch, tx when RTS low[1]
> > Both Tx/Rx Disabled.
> >
> > I guess you were using either option 2 or 3 with that.
> Yes
> > These various modes are handled by the hardware and you can switch
> > them just be setting the register appropriately. Assuming kernel
> Setting the register ? No no, how do you know its a PC 165x0 UART. This
> worked with all serial boards because it was done properly using
> ioctl( TIOCMBIS/TIOCMBIC and friends)

Sorry, I mis explained it, I haven't taken that much of a leave of
my senses , at least I don't think so.

The card has auto support in hardware for those options, outside of
the uart. Options 2/3 you can obviously implement this way with
ioctl( TIOCMBIS/TIOCMBIC and friends) but in this card you need to
enable that option first anyway.

This mean we have three options as I see it.

        1) Chose one, and that what linux supports,
             then do ostrich impression
        2) (1a really) Chose one mode as default make userspace
             bang the h/w directly to change it.

        3) Add a (new?) ioctl to change it. Define a default.

Does this explain it better?

     Think of the mess on the carpet. Sensible people do all their
     demon-summoning in the garage, which you can just hose down afterwards.

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