From patchwork Fri Oct 13 18:35:42 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mika Westerberg X-Patchwork-Id: 10005679 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 65DBD60325 for ; Fri, 13 Oct 2017 18:37:12 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5D1B7290F8 for ; Fri, 13 Oct 2017 18:37:12 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 51E292913B; Fri, 13 Oct 2017 18:37:12 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CF9C1290F8 for ; Fri, 13 Oct 2017 18:37:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751586AbdJMSg5 (ORCPT ); Fri, 13 Oct 2017 14:36:57 -0400 Received: from mga09.intel.com ([134.134.136.24]:12752 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751165AbdJMSgy (ORCPT ); Fri, 13 Oct 2017 14:36:54 -0400 Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Oct 2017 11:36:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,372,1503385200"; d="scan'208";a="909720853" Received: from black.fi.intel.com ([10.237.72.28]) by FMSMGA003.fm.intel.com with ESMTP; 13 Oct 2017 11:36:50 -0700 Received: by black.fi.intel.com (Postfix, from userid 1001) id 23931FB; Fri, 13 Oct 2017 21:35:49 +0300 (EEST) From: Mika Westerberg To: Bjorn Helgaas Cc: Ashok Raj , Keith Busch , "Rafael J . Wysocki" , Lukas Wunner , Michael Jamet , Yehezkel Bernat , Mario.Limonciello@dell.com, Mika Westerberg , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/8] PCI: Open-code the two pass loop when scanning bridges Date: Fri, 13 Oct 2017 21:35:42 +0300 Message-Id: <20171013183548.68283-3-mika.westerberg@linux.intel.com> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171013183548.68283-1-mika.westerberg@linux.intel.com> References: <20171013183548.68283-1-mika.westerberg@linux.intel.com> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The current scanning code is really hard to understand because it calls the same function in a loop where pass value is changed without any comments explaining it: for (pass = 0; pass < 2; pass++) for_each_pci_bridge(dev, bus) max = pci_scan_bridge(bus, dev, max, pass); Unfamiliar reader cannot tell easily what is the purpose of this loop without looking at internals of pci_scan_bridge(). In order to make this bit easier to understand, open-code the loop in pci_scan_child_bus() and pci_hp_add_bridge() with added comments. No functional changes intended. Signed-off-by: Mika Westerberg --- drivers/pci/probe.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 7302cef51d3f..107052f1dad9 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2398,7 +2398,7 @@ void __weak pcibios_fixup_bus(struct pci_bus *bus) unsigned int pci_scan_child_bus(struct pci_bus *bus) { - unsigned int devfn, pass, max = bus->busn_res.start; + unsigned int devfn, max = bus->busn_res.start; struct pci_dev *dev; dev_dbg(&bus->dev, "scanning bus\n"); @@ -2420,9 +2420,17 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus) bus->is_added = 1; } - for (pass = 0; pass < 2; pass++) - for_each_pci_bridge(dev, bus) - max = pci_scan_bridge(bus, dev, max, pass); + /* + * Scan bridges that are already configured. We don't touch them + * unless they are misconfigured (which will be done in the second + * scan below). + */ + for_each_pci_bridge(dev, bus) + max = pci_scan_bridge(bus, dev, max, 0); + + /* Scan bridges that need to be reconfigured */ + for_each_pci_bridge(dev, bus) + max = pci_scan_bridge(bus, dev, max, 1); /* * Make sure a hotplug bridge has at least the minimum requested @@ -2739,7 +2747,7 @@ void __init pci_sort_breadthfirst(void) int pci_hp_add_bridge(struct pci_dev *dev) { struct pci_bus *parent = dev->bus; - int pass, busnr, start = parent->busn_res.start; + int busnr, start = parent->busn_res.start; int end = parent->busn_res.end; for (busnr = start; busnr <= end; busnr++) { @@ -2751,8 +2759,13 @@ int pci_hp_add_bridge(struct pci_dev *dev) pci_name(dev)); return -1; } - for (pass = 0; pass < 2; pass++) - busnr = pci_scan_bridge(parent, dev, busnr, pass); + + /* Scan bridges that are already configured */ + busnr = pci_scan_bridge(parent, dev, busnr, 0); + + /* Scan bridges that need to be reconfigured */ + pci_scan_bridge(parent, dev, busnr, 1); + if (!dev->subordinate) return -1;