Return-Path: <linux-kernel-owner+willy=40w.ods.org@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id <S267427AbTALTlB>; Sun, 12 Jan 2003 14:41:01 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org
	id <S267431AbTALTlB>; 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 <S267427AbTALTkz>; Sun, 12 Jan 2003 14:40:55 -0500
Subject: Re: Linux 2.4.21-pre3-ac4
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Alan Cox <alan@redhat.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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
Content-Length: 1077
Lines: 27

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.

-
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/