From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: Polling (was Re: [PATCHSET 2/2] implement PMP support, take 6) Date: Fri, 28 Sep 2007 22:24:55 -0700 Message-ID: <46FDE1A7.6030102@gmail.com> References: <1190521193410-git-send-email-htejun@gmail.com> <46F9BF3E.5050708@garzik.org> <46FA1B4E.8090103@gmail.com> <46FD079F.3010007@garzik.org> <46FD0D50.8030602@gmail.com> <46FD1C4A.8010101@garzik.org> <46FD306C.3050205@gmail.com> <46FD5DE1.8000206@rtr.ca> <20070928220309.7c9ed816@the-village.bc.nu> <46FDADD9.9050007@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from wa-out-1112.google.com ([209.85.146.176]:34950 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751058AbXI2F0k (ORCPT ); Sat, 29 Sep 2007 01:26:40 -0400 Received: by wa-out-1112.google.com with SMTP id v27so3775449wah for ; Fri, 28 Sep 2007 22:26:39 -0700 (PDT) In-Reply-To: <46FDADD9.9050007@garzik.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: Alan Cox , Mark Lord , linux-ide@vger.kernel.org Jeff Garzik wrote: > Polling ALREADY makes the job of fixing SAS/SATA exception handling > difficult. Expanding polling to something SAS/SATA controllers treat as > fundamentally irq-driven and integrated with the rest of the command > flow is moving in the wrong direction. > > To re-re-re-summarize, polling in PMP is fundamentally broken for an > ENTIRE CLASS OF HARDWARE that we actively support today. And > jgarzik/misc-2.6.git#sas is adding two more controllers to that list. As an interim solution, it doesn't make anything worse tho. Those drivers don't support PMP anyway. After rc1 merge, polling PMP access can be replaced with new qc_issue (probably ata_exec_internal) based code. The question here is whether it's worth to include PMP support with polling PMP register access as an interim solution for 2.6.24. I think it will be beneficial for both user convenience and testing as long as the said change is made soon after -rc1. My vote is yes but this kind of decision ultimately falls on the subsystem maintainer, so it's your call, Jeff. Thanks. -- tejun