From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 27 Jan 2001 12:03:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 27 Jan 2001 12:03:33 -0500 Received: from [194.213.32.137] ([194.213.32.137]:50692 "EHLO bug.ucw.cz") by vger.kernel.org with ESMTP id ; Sat, 27 Jan 2001 12:03:28 -0500 Message-ID: <20010127132847.A485@bug.ucw.cz> Date: Sat, 27 Jan 2001 13:28:47 +0100 From: Pavel Machek To: Brian Gerst , root@chaos.analogic.com Cc: Manfred Spraul , rjohnson@analogic.com, linux-kernel@vger.kernel.org Subject: Re: Linux Post codes during runtime, possibly OT In-Reply-To: <3A71A6DB.B7921B62@didntduck.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.93i In-Reply-To: <3A71A6DB.B7921B62@didntduck.org>; from Brian Gerst on Fri, Jan 26, 2001 at 11:33:31AM -0500 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > > + * > > > > + * Changed the slow-down I/O port from 0x80 to 0x19. 0x19 is a > > > > + * DMA controller scratch register. rjohnson@analogic.com > > > > */ > > > > > > > What about making that a config option? > > > > > > default: delay with 'outb 0x80', other options could be > > > udelay(n); (n=1,2,3) > > > outb 0x19 > > > > > > 0x80 is a safe port, and IMHO changing the port on all i386 systems > > > because it's needed for some embedded system debuggers is too dangerous. > > > > > Dangerous? udelay(1) on a 33 MHz system is like udelay(100). Don't > > get too used to 800+ MHz CPUs. There are systems, probably most in > > the world, that need 300 +/- nanosecond delays. This is what the > > port I/O does. > > In most of the cases where this delay is needed, it is a _minimum_ > delay. It is usually time enough for the hardware to react to an index > register being written to, etc. In most cases, a longer delay on slower > machines should not hurt. Except getting your ne2000 slower by factor of 300. Pavel -- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/