Date: Wed, 22 Jan 1997 05:39:43 +1100 From: Bruce Evans <bde@zeta.org.au> To: freebsd-hackers@freebsd.org, luoqi@watermarkgroup.com Subject: Re: My sportster internal modem doesn't work after switched to 2.2-BETA Message-ID: <199701211839.FAA14689@godzilla.zeta.org.au>
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>After some poking around, I found that the if I sent multiple bytes >to the modem, some would get lost. So I went to sio.c and changed >com->tx_fifo_size to 1 from 16, and everything works fine now. >But I am still wondering if this is a problem with the modem, or with >the software. It seems that NT is doing the same, sending no more than >one >byte at a time. This is not a satisfactory solution, the output FIFO >is underutilized and CPU is servicing 16 times more interrupts. Which version did it work in? The sio driver streams output better than it used to. There used to be a small amount of dead time every 256(?) characters. Perhaps the internal modem can't quite keep up and its flow control doesn't work or you're not using flow control. Reducing com->tx_fifo_size gives flow control a better chance of working. Try other values < 16 for com->tx_fifo_size. Bruce
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