From owner-freebsd-hackers Wed Oct 27 22:50:17 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from dingo.cdrom.com (castles529.castles.com [208.214.165.93]) by hub.freebsd.org (Postfix) with ESMTP id 8602E14E44 for ; Wed, 27 Oct 1999 22:50:14 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Received: from dingo.cdrom.com (localhost [127.0.0.1]) by dingo.cdrom.com (8.9.3/8.8.8) with ESMTP id WAA01326; Wed, 27 Oct 1999 22:41:31 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Message-Id: <199910280541.WAA01326@dingo.cdrom.com> X-Mailer: exmh version 2.0.2 2/24/98 To: eT@post.com Cc: hackers@freebsd.org Subject: Re: PCI bus Latency In-reply-to: Your message of "Wed, 27 Oct 1999 01:35:57 PDT." <19991027083557.22017.rocketmail@web1402.mail.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 27 Oct 1999 22:41:30 -0700 From: Mike Smith Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Please try wrapping your messages to a sane width; try 72 columns. > When doing a pci_read_config(dev, PCI_LATENCY_TIMER, 4) I get varying > values on different hardware configurations. > > On Machine A the value is 32 and my device driver (using DMA) works fine. > > On Machine B the value is 64 and my device driver doesn't work fine - > there seem s to be these hickups in which the Chip writing to the PCI > controller says it has finished transferring data but the write > counters are still > 0. My card works closely with two network cards in > the system. Since you don't make it clear what "the Chip" and "the PCI controller" are, it's kinda hard to be very helpful here. > Actually, I reckon I just need some pointers and things to remember when it > comes to dealing with latency. Any help? I'd start by buying and reading the PCI specification document end to end. You can probably skip the section on physical dimensions, but just about all of the rest of it is relevant. You can save a little time and a lot of money by getting a copy of the Shanley book "PCI System Architecture". Most online bookstores have it; it's cheap. Without meaning to be insulting, it's probably not worthwhile pursuing this further until you've read one or both of the above, since we'd just be regurgitating large portions of the books. Buy, read, and if you're still having trouble then come back and try again. 8) -- \\ Give a man a fish, and you feed him for a day. \\ Mike Smith \\ Tell him he should learn how to fish himself, \\ msmith@freebsd.org \\ and he'll hate you for a lifetime. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message