From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423933AbcBQPfi (ORCPT ); Wed, 17 Feb 2016 10:35:38 -0500 Received: from mail-wm0-f44.google.com ([74.125.82.44]:38617 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423909AbcBQPfe (ORCPT ); Wed, 17 Feb 2016 10:35:34 -0500 Subject: Re: [PATCH V5 07/15] pci, acpi: Provide generic way to assign bus domain number. To: Jayachandran Chandrashekaran Nair References: <1455630825-27253-1-git-send-email-tn@semihalf.com> <1455630825-27253-8-git-send-email-tn@semihalf.com> <56C47E9A.5010901@semihalf.com> <56C48C45.7050203@semihalf.com> Cc: Bjorn Helgaas , Arnd Bergmann , will.deacon@arm.com, catalin.marinas@arm.com, rafael@kernel.org, Hanjun Guo , Lorenzo Pieralisi , okaya@codeaurora.org, jiang.liu@linux.intel.com, Jayachandran Chandrashekaran Nair , Stefano Stabellini , robert.richter@caviumnetworks.com, Marcin Wojtas , Liviu.Dudau@arm.com, David Daney , wangyijing@huawei.com, Suravee.Suthikulpanit@amd.com, msalter@redhat.com, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linaro-acpi@lists.linaro.org, jcm@redhat.com From: Tomasz Nowicki Message-ID: <56C49342.1070308@semihalf.com> Date: Wed, 17 Feb 2016 16:35:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17.02.2016 16:21, Jayachandran Chandrashekaran Nair wrote: > On Wed, Feb 17, 2016 at 8:35 PM, Tomasz Nowicki wrote: >> On 17.02.2016 15:21, Jayachandran Chandrashekaran Nair wrote: >>> >>> On Wed, Feb 17, 2016 at 7:37 PM, Tomasz Nowicki wrote: >>>> >>>> On 17.02.2016 14:44, Jayachandran Chandrashekaran Nair wrote: >>>>> >>>>> >>>>> Tomasz, Lorenzo, >>>>> >>>>> On Tue, Feb 16, 2016 at 7:23 PM, Tomasz Nowicki wrote: >>>>>> >>>>>> >>>>>>> As we now have valid PCI host bridge device reference we can >>>>>>> introduce code that is going to find its bus domain number using >>>>>>> ACPI _SEG method. >>>>>>> >>>>>>> Note that _SEG method is optional, therefore _SEG absence means >>>>>>> that all PCI buses belong to domain 0. >>>>>>> >>>>>>> While at it, for the sake of code clarity we put ACPI and DT domain >>>>>>> assign methods into the corresponding helpers. >>>>> >>>>> >>>>> In my patchset, I had a slightly different and I think better approach >>>>> for >>>>> this without calling the _SEG method again. Please see >>>>> http://www.spinics.net/lists/arm-kernel/msg478167.html >>>>> at the last part >>>>> ofhttp://www.spinics.net/lists/arm-kernel/msg478169.html >>>> >>>> >>>> Relying on NULL parent device to make decision on boot method is really >>>> ugly >>>> way. This may hit us again once we want to obtain another firmware >>>> specific >>>> info e.g. numa node. IMO we need to fix it this way. >>> >>> >>> I am not relying on NULL there, in the current code parent is NULL >>> in case of ACPI, and the check is needed not to crash (unless that >>> has changed). >> >> >> This series passes down valid parent, see [PATCH V5 06/15]. >> >>> >>> The main part was the macro acpi_pci_get_segment() and the use >>> of acpi_pci_root_info from sysdata to do this. >> >> >> Since we can obtain related firmware specific data from valid parent device >> (without defining another accessors), I do not see the point to use sysdata. >> Let me know your opinion. > > In the patch, you use the parent info and call _SEG method again. > The segment information is available in the ->root->segment of > acpi_pci_root_info if you setup the sysdata like in my patch I know it is in sysdata->root->segment, but the way it is passed down is wrong. sysdata is the pointer to unknown content (void *) so we need to validate it before we can use it. If we merge this patch we can remove first _SEG call. Tomasz