Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759666AbWLCNNL (ORCPT ); Sun, 3 Dec 2006 08:13:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759668AbWLCNNL (ORCPT ); Sun, 3 Dec 2006 08:13:11 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:51333 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1759666AbWLCNNJ (ORCPT ); Sun, 3 Dec 2006 08:13:09 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Stefan Reinauer Cc: Segher Boessenkool , Peter Stuge , linux-kernel@vger.kernel.org, linuxbios@linuxbios.org Subject: Re: [LinuxBIOS] #57: libusb host program for PLX NET20DC debug device References: <5986589C150B2F49A46483AC44C7BCA490727C@ssvlexmb2.amd.com> <2ea3fae10612021247v33cfaa4evbc8ad1d5eaf196ba@mail.gmail.com> <20061203120130.GA32458@coresystems.de> <77E505A2-6E0B-422F-92AB-97395730A522@kernel.crashing.org> <20061203125250.GA17019@coresystems.de> Date: Sun, 03 Dec 2006 06:11:57 -0700 In-Reply-To: <20061203125250.GA17019@coresystems.de> (Stefan Reinauer's message of "Sun, 3 Dec 2006 13:52:50 +0100") Message-ID: User-Agent: Gnus/5.110004 (No Gnus v0.4) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1359 Lines: 31 Stefan Reinauer writes: > * Segher Boessenkool [061203 13:42]: >> On LPC, yes -- or 0.5us or something like that. On ISA it's >> a lot faster, on PCI too -- better do 20 or so outb's to be >> safe. > > The value's actually something we have been using as a rule of thumb > while doing outb to port 80. Don't think these are routed to LPC, are > they? Depends on the destination address. For 0x80 you can be fairly certain it will be an unacknowledged cycle subtractively decoded to the slowest bus on the system. Or routed to 32 PCI or the LPC bus if there is something to actually looking at the value so it is slow. Since all I need is something that delays for about 50ms 50,000 outb to port 0x80 looks like a good first approximation, and since it only happens once it is probably better to just bump that count up instead of trying to be precise about it and have an accurate timer. I'm not at all convinced a usb console can be made sufficiently solid to be useful. But it is at least worth trying so we can clearly say it doesn't work well. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/