Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755072Ab0AQWhQ (ORCPT ); Sun, 17 Jan 2010 17:37:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754813Ab0AQWhO (ORCPT ); Sun, 17 Jan 2010 17:37:14 -0500 Received: from hera.kernel.org ([140.211.167.34]:37764 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932087Ab0AQWhM (ORCPT ); Sun, 17 Jan 2010 17:37:12 -0500 Message-ID: <4B5390B7.5000801@kernel.org> Date: Sun, 17 Jan 2010 14:35:35 -0800 From: Yinghai Lu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091130 SUSE/3.0.0-1.1.1 Thunderbird/3.0 MIME-Version: 1.0 To: Jesse Barnes CC: Bjorn Helgaas , Alex Chiang , Ingo Molnar , Linus Torvalds , Ivan Kokshaysky , Kenji Kaneshige , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH 10/11] pciehp: add support for bridge resource reallocation References: <1263609721-3921-1-git-send-email-yinghai@kernel.org> <1263609721-3921-11-git-send-email-yinghai@kernel.org> <20100116045911.GI22215@ldl.fc.hp.com> <4B518815.70006@kernel.org> <1263683671.29907.47.camel@dc7800.home> <20100117093418.6d545b43@jbarnes-piketon> In-Reply-To: <20100117093418.6d545b43@jbarnes-piketon> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2408 Lines: 63 On 01/17/2010 09:34 AM, Jesse Barnes wrote: > On Sat, 16 Jan 2010 16:14:31 -0700 > Bjorn Helgaas wrote: > >> On Sat, 2010-01-16 at 01:34 -0800, Yinghai Lu wrote: >>> On 01/15/2010 08:59 PM, Alex Chiang wrote: >>>> * Yinghai Lu : >>>>> From: Kenji Kaneshige >>>>> >>>>> With this patch, pciehp driver try to clear PCI bridge resources >>>>> to parent bridge (root port or switch downstream port) of the >>>>> slot >>>>> >>>>> so we can shrink pci bridge resource for those port >>>>> >>>>> This feature is enabled when 'pciehp_realloc' option is >>>>> specified. >>>>> >>>>> -v2: make it could be appiled after Yinghai patchset that touch >>>>> pci bridge resource also remove poweron check, because >>>>> pci_bridge_release_res will check child at first >>>> >>>> Same comment as my earlier patch. Why not just make this the >>>> default behavior, instead of introducing yet another command line >>>> parameter for users to guess at? >>> >>> it will break Eric's setup/ >> >> I think this is a clue that we don't understand the problem well >> enough yet. >> >> I'm opposed to adding kernel parameters for this sort of thing. It is >> unreasonable to expect users to figure out whether they need to use >> this parameter or not. >> >> Special-case switches like this make it much harder to maintain the >> code in the future. > > Agreed. Yinghai, what's wrong in the new reassignment code that > causes Eric's setup to break? Can we just fix that instead and enable > reallocation by default? no. Eric's setup is: hot plug one addon card into one hotplug slots and new addon cards have more hot plug slots. SLOTA will have SLOT B, SLOT C, and SLOT D as children. and not devices in SLOTB/C/D at first. with the pciehp_realloc is specified, the SLOTA will not get any device assigned, and later if put devices in SLOTB/SLOTC/SLOTD, will not get resource for those devices. and we can not go above to update SLOT A, because: some devices on SLOTB could already have driver loaded. if you don't like pciehp_realloc at this point, please only apply 1-8 and 11. Thanks Yinghai Lu -- 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/