Date: Sun, 24 Dec 1995 00:29:04 +1100 From: Bruce Evans <bde@zeta.org.au> To: freebsd-hackers@freefall.freebsd.org, michael.class@zdv.uni-tuebingen.de Subject: Re: fbsd-current stability / sio-problem Message-ID: <199512231329.AAA24417@godzilla.zeta.org.au>
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>Teh recent changes in sio.c that add support for some chips called
>16650 make my ppp-access hanging. The problem is that my 16550-chips
>...
The buggy probe was disabled yesterday.
> i = inb(iobase + com_iir);
>printf(" i: %0x,",i);
> outb(iobase + com_cfcr, 0xff);
> outb(iobase + com_iir, 0x0);
> outb(iobase + com_cfcr, CFCR_8BITS);
> j = inb(iobase + com_iir);
>printf(" j: %0x,",j);
>...
>The added printfs show 0xC1 for i and j on booting!
On a real 16550, i should be 0xC1 and j should be 0x01. com_iir here
should probably be called com_fifo. It's confusing to have several
registers at the same address. Here the middle outb writes to another
register at com_fifo for 16650s and to the standard com_fifo register
for 16550s. Writing 0 should turn off the fifo for 16550s only, and
the 0xC0 bits should be off when the fifo is off.
Bruce
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