From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 26 Jan 2001 11:34:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 26 Jan 2001 11:34:42 -0500 Received: from [64.64.109.142] ([64.64.109.142]:33540 "EHLO quark.didntduck.org") by vger.kernel.org with ESMTP id ; Fri, 26 Jan 2001 11:34:26 -0500 Message-ID: <3A71A6DB.B7921B62@didntduck.org> Date: Fri, 26 Jan 2001 11:33:31 -0500 From: Brian Gerst X-Mailer: Mozilla 4.73 [en] (WinNT; U) X-Accept-Language: en MIME-Version: 1.0 To: 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: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org "Richard B. Johnson" wrote: > > On Fri, 26 Jan 2001, Manfred Spraul wrote: > > > > + * > > > + * 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. -- Brian Gerst - 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/