Re: PATCH: serial patch for PPC

tytso@mit.edu
Tue, 28 Sep 1999 19:47:20 -0400


Date: Wed, 29 Sep 1999 07:17:23 +1000
From: Paul Mackerras <paulus@cs.anu.edu.au>

Well, it's more a question of who is grabbing minor numbers 64 and up
on the TTY_MAJOR/TTY_AUX_MAJOR major numbers, and the answer is that
is the driver for the Z8530-based serial ports, macserial.c. It does
that because I based it on the zs.c serial driver for the Sparc, which
also does that.

That shouldn't be causing a problem, though, as long as PPC systems are
either/or as far as Z8530 or 16550 UARTs are concerned.

The tty_register_driver code currently doesn't mind if there is overlap
in the minor number space, actually. The most recently loaded driver
wins. The only time when register_tty_driver() will fail is if the
major number has already been grabbed by a non-tty driver. That's why I
don't like the patch which simply ignores the error. If
tty_register_driver() is failing, there's some kind of device driver
conflict that we should understand.

- Ted

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