Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754952AbXABV3H (ORCPT ); Tue, 2 Jan 2007 16:29:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755421AbXABV3G (ORCPT ); Tue, 2 Jan 2007 16:29:06 -0500 Received: from srv5.dvmed.net ([207.36.208.214]:46779 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754952AbXABV3F (ORCPT ); Tue, 2 Jan 2007 16:29:05 -0500 Message-ID: <459ACE9C.7020107@pobox.com> Date: Tue, 02 Jan 2007 16:29:00 -0500 From: Jeff Garzik User-Agent: Thunderbird 1.5.0.9 (X11/20061219) MIME-Version: 1.0 To: Alan CC: Linus Torvalds , Alessandro Suardi , Linux Kernel Mailing List Subject: Re: [PATCH] libata: fix combined mode (was Re: Happy New Year (and v2.6.20-rc3 released)) References: <5a4c581d0701010528y3ba05247nc39f2ef096f84afa@mail.gmail.com> <459973F6.2090201@pobox.com> <20070102115834.1e7644b2@localhost.localdomain> <459AC808.1030807@pobox.com> <20070102212701.4b4535cf@localhost.localdomain> In-Reply-To: <20070102212701.4b4535cf@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.3 (----) X-Spam-Report: SpamAssassin version 3.1.7 on srv5.dvmed.net summary: Content analysis details: (-4.3 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2197 Lines: 64 Alan wrote: >>> This is a silly complaint because the SFF layer in libata doesn't handle >>> this case yet anyway. >> Yes, it's "silly" people people use configurations you find inconvenient. >> >> At least one embedded x86 case cares, that I know of. They only needed >> to make two minor changes to make it work. > > *It is not part of 2.6.20* > >> The code no long reserves resources for the "extra" PCI BAR that often >> exists on PCI controllers regardless of legacy/native mode. Previously, >> the code called pci_request_regions() to reserve ALL regions attached to >> the PCI device. > > We use BAR5 on two devices in legacy mode. Both of those reserve all the > other resources. Translation: You want to hand-wave away an obvious regression that YOU have created with your fix-to-a-fix. > We can fix BAR5 in .21 when all the combined mode crap > goes away. Translation: Problems disappear in 2.6.21 because Jeff will revert the code I touched to its previous state -- always calling pci_request_regions() -- and all the problems I introduced by avoiding pci_request_regions() will go away. Why INTRODUCE these 2.6.20 Alan-isms, if they are going away in 2.6.21? >> You have suddenly decided that it's OK to --not reserve at all-- these >> additional regions. > > It's not ideal - but it is perfectly sufficient for 2.6.20 > >> Proof: The AHCI PCI BAR (#5, zero-based) is clearly NOT reserved, even >> though we talk to it, in piix_disable_ahci() of ata_piix.c. > > We always claim the other BARs so catch a collision. Where? AFAICS, it is crystal clear the behavior: * Prior to your patch, ata_piix in legacy mode calls pci_request_regions() to intentionally reserve ALL regions on the PCI device. * After your patch, the code explicitly calls pci_request_region() for BARs 0-4, but never for BAR5. Another driver is now free to claim a PCI BAR, and start running the hardware in AHCI mode, whee! Jeff - 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/