From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCHSET] implement and use port_task Date: Tue, 07 Mar 2006 02:21:09 -0500 Message-ID: <440D3465.1040203@pobox.com> References: <11415401073423-git-send-email-htejun@gmail.com> <440D2497.7050504@tw.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.dvmed.net ([216.237.124.58]:63679 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S932415AbWCGHVS (ORCPT ); Tue, 7 Mar 2006 02:21:18 -0500 In-Reply-To: <440D2497.7050504@tw.ibm.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: albertl@mail.com Cc: Tejun Heo , linux-ide@vger.kernel.org Albert Lee wrote: > Something related to the PIO HSM. > After the task renaming by this patchset, the task name is changed from pio_task to port_task. > Should we add polling DMA support to the polling HSM? > It could make the polling HSM more complete. > > Polling DMA does no performance gain. However, DMA has crc check, > so it won't be worse than PIO when irq is not working. 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. Jeff