From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 12 Jan 2003 14:41:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 12 Jan 2003 14:41:01 -0500 Received: from AMarseille-201-1-1-174.abo.wanadoo.fr ([193.252.38.174]:47217 "EHLO zion.wanadoo.fr") by vger.kernel.org with ESMTP id ; Sun, 12 Jan 2003 14:40:55 -0500 Subject: Re: Linux 2.4.21-pre3-ac4 From: Benjamin Herrenschmidt To: Alan Cox Cc: Alan Cox , Linux Kernel Mailing List In-Reply-To: <1042403235.16288.14.camel@irongate.swansea.linux.org.uk> References: <200301121807.h0CI7Qp04542@devserv.devel.redhat.com> <1042399796.525.215.camel@zion.wanadoo.fr> <1042403235.16288.14.camel@irongate.swansea.linux.org.uk> Content-Type: text/plain Content-Transfer-Encoding: 7bit Organization: Message-Id: <1042401074.525.219.camel@zion.wanadoo.fr> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.0 Date: 12 Jan 2003 20:51:14 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2003-01-12 at 21:27, Alan Cox wrote: > which currently has two problems Ross found > > 1. The processors or so fast we have to enforce the 400nS delay nowdays What about PCI write posting ? How can we enforce the 400ns delay here ? I suspect we can't read back from the taskfile registers after writing the command. Especially when using DMA, I think I remember Andre telling me even tapping alt status might not be safe... So we need to issue a read from the same bus path, but not on any taskfile register from this channel... hrm... any idea ? > 2. The code is racey in some situations with a shared IRQ because we > may get an IRQ after we set the handler but before we send the command, > or implemnted the other way the command can complete before we set the > handler. Yup, that's an old problem indeed. Ben.