From owner-freebsd-hackers Sun Mar 2 10:23:12 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id KAA24192 for hackers-outgoing; Sun, 2 Mar 1997 10:23:12 -0800 (PST) Received: from horst.bfd.com (horst.bfd.com [204.160.242.10]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id KAA24178 for ; Sun, 2 Mar 1997 10:23:06 -0800 (PST) Received: from harlie.bfd.com (bastion.bfd.com [204.160.242.14]) by horst.bfd.com (8.8.5/8.7.3) with SMTP id KAA24361; Sun, 2 Mar 1997 10:23:02 -0800 (PST) Date: Sun, 2 Mar 1997 10:23:01 -0800 (PST) From: "Eric J. Schwertfeger" To: Bruce Evans cc: freebsd-hackers@FreeBSD.ORG Subject: Re: sio projects In-Reply-To: <199703021810.FAA27377@godzilla.zeta.org.au> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk On Mon, 3 Mar 1997, Bruce Evans wrote: > >1) Autodetect the UARTS, and use their deeper fifos. > > There is already some support for this (for 16550s) in sio.c. It is > disabled because it doesn't quite work. I think auto-detection works. I'd be surprized if the fifo's are actually disabled, as it's hard to get unix to do better than 19.2kbaud without them. I suspect that the threshold might be set to 1, but that's different than disabling them. I'd have gone through the source to sio.c by now, but my printer jammed horribly. Oh, and by autodetect, I meant tell the difference between the 550/650/750. > >3) Throw in a flag to use the UART-driven hardware flow control methods. > > The hardware flow control on at least the original 16550's is reported > to be worse that useless because it is invoked at the wrong time - at > the same time that a fifo-trigger-level-reached interrupt is generated > or something like that - it breaks streaming. Sorry, should have been more specific.. I meant for the 650/750, for which this supposedly was fixed. Maybe set it up to ignore the flag on 550 chips?