From mboxrd@z Thu Jan 1 00:00:00 1970 From: Albert Lee Subject: Re: [PATCHSET] implement and use port_task Date: Thu, 09 Mar 2006 16:39:50 +0800 Message-ID: <440FE9D6.9040006@tw.ibm.com> References: <11415401073423-git-send-email-htejun@gmail.com> <440D2497.7050504@tw.ibm.com> <440D3465.1040203@pobox.com> Reply-To: albertl@mail.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from e33.co.us.ibm.com ([32.97.110.151]:29589 "EHLO e33.co.us.ibm.com") by vger.kernel.org with ESMTP id S1750740AbWCIIkC (ORCPT ); Thu, 9 Mar 2006 03:40:02 -0500 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e33.co.us.ibm.com (8.12.11/8.12.11) with ESMTP id k298duBr014302 for ; Thu, 9 Mar 2006 03:39:56 -0500 Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay04.boulder.ibm.com (8.12.10/NCO/VER6.8) with ESMTP id k298gkR7178706 for ; Thu, 9 Mar 2006 01:42:46 -0700 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.12.11/8.13.3) with ESMTP id k298dtdE024499 for ; Thu, 9 Mar 2006 01:39:55 -0700 In-Reply-To: <440D3465.1040203@pobox.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: albertl@mail.com, Tejun Heo , linux-ide@vger.kernel.org Jeff Garzik wrote: > > > Polling DMA support with nIEN=1 is theoretically invalid. You are not > supposed to touch the ATA shadow register set until after receiving an > irq event. > > On chipsets where nIEN=0 and the chip's IntrMask is also zero, its doable. > > I'm satisfied with simply never doing polling DMA, and change our mind > only if a critical need arises. > > Understand. After checking the code, polling DMA looks bad idea. Thanks for the advice. BTW, Tejun's proposal of pseudo periodic interrupts reminds me of some patches to integrate the polling pio with irq-pio. Will submit the patches for your review later. Albert