Date: Tue, 4 Jul 1995 14:55:29 +0500 (GMT+0500) From: "Serge A. Babkin" <babkin@hq.icb.chel.su> To: bde@zeta.org.au (Bruce Evans) Cc: hackers@freebsd.org Subject: Re: Minor for Digiboard driver Message-ID: <199507040955.OAA03586@hq.icb.chel.su> In-Reply-To: <199507040555.PAA11661@godzilla.zeta.org.au> from "Bruce Evans" at Jul 4, 95 03:55:36 pm
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>
> >>My developing of Digiboard driver came to the point where I need
> >>a major number. Give me one please.
>
> > Just pick the next available one. If we need to re-assign it before
> >committing the driver (very unlikely), then that's okay.
>
> We're close to needing a single major number for all ttys (like sd has
> a single major number for all scsi controllers). You need a new major
> now, however. Please be careful not to implement any ioctl or minor
> number magic that is inconsistent with the other drivers (sio, cy and
> rc; cx and ity are already inconsistent).
I took the scheme for minor numbers from sio, the only thing I added
is 2 bits of card number :
not_used{14} card_number{2} major{8} sio_like_minor{8}
The only problem is that I don't know how to name the special files to
be consistent with existing conventions. I know Peter Wemm who wrote
Specialix card driver had the same problem and I'll ask him about his
decision.
> Did you use any "intelligent" features of the Digiboard? Minor design
I use its big buffers and flow control features. It has some ability
to do the canonical processing but I don't know how to use it because
Linux driver doesn't uses it.
> characters caused overrun errors. I thought had the cd1400 working
> slightly more efficiently than a 16550, but that was only with an
> input fifo size that was too large to avoid overruns. To avoid
> overruns for just 2 active ports, the input fifo size has to be 6,
> while 14 works for 16550's and is considerably more efficient.
I think Digi should be more efficient due to its big buffers in
dual-ported memory.
Serge Babkin
! (babkin@hq.icb.chel.su)
! Headquarter of Joint Stock Commercial Bank "Chelindbank"
! Chelyabinsk, Russia
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