From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754574AbXLUSCB (ORCPT ); Fri, 21 Dec 2007 13:02:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752086AbXLUSBw (ORCPT ); Fri, 21 Dec 2007 13:01:52 -0500 Received: from relay1.sgi.com ([192.48.171.29]:57843 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751402AbXLUSBw (ORCPT ); Fri, 21 Dec 2007 13:01:52 -0500 From: akepner@sgi.com Date: Fri, 21 Dec 2007 10:00:22 -0800 To: Benjamin Herrenschmidt Cc: Stefan Richter , Andrew Morton , grundler@parisc-linux.org, jbarnes@virtuousgeek.org, jes@sgi.com, randy.dunlap@oracle.com, rdreier@cisco.com, James.Bottomley@steeleye.com, davem@davemloft.net, linux-kernel@vger.kernel.org Subject: Re: [RFC] dma: passing "attributes" to dma_map_* routines Message-ID: <20071221180022.GW412@sgi.com> References: <20071218001758.GO21916@sgi.com> <4767FA62.9060002@s5r6.in-berlin.de> <20071218200759.GE412@sgi.com> <1198184185.6779.16.camel@pasglop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1198184185.6779.16.camel@pasglop> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 21, 2007 at 07:56:25AM +1100, Benjamin Herrenschmidt wrote: > ... > Can't you just have a primitive to sync things up that you call > explicitely from your driver after fetching a new status entry ? > Well, the only mechanisms I know to get things synced are the ones I mentioned before: 1) generate an interrupt, 2) write to memory which has the "barrier" attribute. Obviously 1 is out - giving the memory used for status indications the barrier attribute is the most primitive means I'm aware of. -- Arthur