From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com [209.85.212.177]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 8FEFD1A09FD for ; Thu, 20 Nov 2014 22:54:57 +1100 (AEDT) Received: by mail-wi0-f177.google.com with SMTP id l15so5058983wiw.16 for ; Thu, 20 Nov 2014 03:54:53 -0800 (PST) Message-ID: <546DD688.60705@linaro.org> Date: Thu, 20 Nov 2014 12:54:48 +0100 From: Tomasz Nowicki MIME-Version: 1.0 To: Arnd Bergmann , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH 00/16] Refine PCI host bridge scan interfaces References: <1416219710-26088-1-git-send-email-wangyijing@huawei.com> <1463511.o4kE8TX3Bd@wuerfel> In-Reply-To: <1463511.o4kE8TX3Bd@wuerfel> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: Liviu Dudau , Tony Luck , Russell King , linux-pci@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Xinwei Hu , Yijing Wang , Thierry Reding , Suravee.Suthikulpanit@amd.com, Bjorn Helgaas , linux-ia64@vger.kernel.org, Thomas Gleixner , Wuyun , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 17.11.2014 15:13, Arnd Bergmann wrote: > On Monday 17 November 2014 18:21:34 Yijing Wang wrote: >> This series is based Linux 3.18-rc1 and Lorenzo Pieralisi's >> arm PCI domain cleanup patches, link: >> https://patchwork.ozlabs.org/patch/407585/ >> >> Current pci scan interfaces like pci_scan_root_bus() and directly >> call pci_create_root_bus()/pci_scan_child_bus() lack flexiblity. >> Some platform infos like PCI domain and msi_chip have to be >> associated to PCI bus by some arch specific function. >> We want to make a generic pci_host_bridge, and make it hold >> the platform infos or hook. Then we could eliminate the lots >> of arch pci_domain_nr, also we could associate some platform >> ops something like pci_get_msi_chip(struct pci_dev *dev) >> with pci_host_bridge to avoid introduce arch weak functions. >> >> This RFC version not for all platforms, just applied the new >> scan interface in x86/arm/powerpc/ia64, I will refresh other >> platforms after the core pci scan interfaces are ok. > > I think overall this is a good direction to take, in particular > moving more things into struct pci_host_bridge so we can > slim down the architecture specific code. > > I don't particularly like the way you use the 'pci_host_info' > to pass callback pointers and some of the generic information. > This duplicates some of the issues we are currently trying > to untangle in the arm32 code to make drivers easier to share > between architectures. > > As a general approach, I'd rather see generic helper functions > being exported by the PCI core that a driver may or may not > call. > The way you split the interface between things that happen > before scanning the buses (pci_create_host_bridge) and > the actual scanning (__pci_create_root_bus, pci_scan_child_bus) > seems very helpful and I think we can expand that concept further: > > - The normal pci_create_host_bridge() function can contain > all of the DT scanning functions (finding bus/mem/io resources, > finding the msi-parent), while drivers that don't depend on DT > for this information can call the same function and fill the > same things after they have the pci_host_bridge pointer. How about finding PCI domain number (in the DT way) within pci_create_host_bridge() too ? Tomasz