From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 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> 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 List-ID: 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; -- 2.14.2