From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753718AbbHFEup (ORCPT ); Thu, 6 Aug 2015 00:50:45 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:46506 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751230AbbHFEun (ORCPT ); Thu, 6 Aug 2015 00:50:43 -0400 Message-ID: <55C2E79E.3090809@roeck-us.net> Date: Wed, 05 Aug 2015 21:50:38 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: Yinghai Lu CC: Bjorn Helgaas , "linux-pci@vger.kernel.org" , Linux Kernel Mailing List , Lorenzo Pieralisi Subject: Re: [PATCH v3] PCI: Only enable IO window if supported References: <1438308908-12259-1-git-send-email-linux@roeck-us.net> <55C2C4F4.1040600@roeck-us.net> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/05/2015 09:25 PM, Yinghai Lu wrote: > On Wed, Aug 5, 2015 at 7:22 PM, Guenter Roeck wrote: >> On 08/05/2015 06:38 PM, Yinghai Lu wrote: >>> >>> On Wed, Aug 5, 2015 at 6:14 PM, Yinghai Lu wrote: >>>> >>>> >>>> It only can avoid warning with bridge, and still have warning on >>>> devices under the bridge. >>>> >>>> also would have problem on transparent bridges, like >>>> >>>> BRIDGE_A ---- BRIDGE_AA----DEVICE_AA >>>> | >>>> \-- BRIDGE_AB ---DEVICE_AB >>>> >>>> if only BRIDGE_A and BRIDGE_AA are transparent, and BRIDGE_AB is not. >>>> >>>> and if pci_bridge_supports_io() return false for BRIDGE_A. >>>> >>>> We will have all three bridges have PCI_BUS_FLAGS_SUPPORTS_IO cleared. >>>> so all will not been sized and will not get assigned io port resource. >>>> >>>> later DEVICE_AA could root bus io port as parent, and get io resource >>>> assigned. >>>> but DEVICE_AB will not get assigned. >>>> >>>> so we should get rid of pci_bridge_supports_io(), and just check root >>>> resource IO port. >>> >>> >>> I would suggest this version instead: >>> >>> Subject: [PATCH] PCI: Only try to assign io port only if root bus support >>> that >>> >> >> Bjorn had asked me to move the IO support check out of >> pci_bridge_check_ranges(). >> It looks like you want to keep it there. >> >> Can you explain your reasons ? Sorry, I just don't understand. > > in pci_alloc_child_bus(), child bus's bus_flags will be assigned with > parent's bus_flags. > > so if one parent bus has bridge's io bar can not changed, then all > children bus will also > have same bus_flags, and their bridge io bar will not used. > > then if BRIDGE_AB is not transparent, we do need to use it's bridge io bar. > If I understand you correctly, we might need to change the code in pci_read_bridge_io() as follows. From if (!(child->bus_flags & PCI_BUS_FLAGS_SUPPORTS_IO)) return; to something like if (!(child->bus_flags & PCI_BUS_FLAGS_SUPPORTS_IO)) { if (dev->transparent) return; child->bus_flags |= PCI_BUS_FLAGS_SUPPORTS_IO; } Would that solve the problem you are concerned about ? Thanks, Guenter