From patchwork Wed Aug 25 06:07:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?6ZmI5Y2O5omN?= X-Patchwork-Id: 1520533 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4GvbFJ0ZC9z9sR4 for ; Wed, 25 Aug 2021 16:10:44 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238209AbhHYGL2 (ORCPT ); Wed, 25 Aug 2021 02:11:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:45508 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237908AbhHYGL1 (ORCPT ); Wed, 25 Aug 2021 02:11:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 765CE613A7; Wed, 25 Aug 2021 06:10:40 +0000 (UTC) From: Huacai Chen To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, Xuefeng Li , Huacai Chen , Jiaxun Yang , Huacai Chen Subject: [PATCH V8 4/5] PCI: Add quirk for LS7A to avoid reboot failure Date: Wed, 25 Aug 2021 14:07:23 +0800 Message-Id: <20210825060724.3385929-5-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210825060724.3385929-1-chenhuacai@loongson.cn> References: <20210825060724.3385929-1-chenhuacai@loongson.cn> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Commit cc27b735ad3a75574a ("PCI/portdrv: Turn off PCIe services during shutdown") causes poweroff/reboot failure on systems with LS7A chipset. We found that if we remove "pci_command &= ~PCI_COMMAND_MASTER;" in do_pci_disable_device(), it can work well. The hardware engineer says that the root cause is that CPU is still accessing PCIe devices while poweroff/reboot, and if we disable the Bus Master Bit at this time, the PCIe controller doesn't forward requests to downstream devices, and also doesn't send TIMEOUT to CPU, which causes CPU wait forever (hardware deadlock). This behavior is a PCIe protocol violation (Bus Master should not be involved in CPU MMIO transactions), and it will be fixed in new revisions of hardware (add timeout mechanism for CPU read request, whether or not Bus Master bit is cleared). On some x86 platforms, radeon/amdgpu devices can cause similar problems [1][2]. Once before I wanted to make a single patch to solve "all of these problems" together, but it seems unreasonable because maybe they are not exactly the same problem. So, this patch just add a quirk for LS7A to avoid clearing Bus Master bit in pcie_port_device_remove(), and leave other platforms as is. [1] https://bugs.freedesktop.org/show_bug.cgi?id=97980 [2] https://bugs.freedesktop.org/show_bug.cgi?id=98638 Signed-off-by: Huacai Chen --- drivers/pci/controller/pci-loongson.c | 20 ++++++++++++++++++++ drivers/pci/pcie/portdrv_core.c | 6 +++++- include/linux/pci.h | 1 + 3 files changed, 26 insertions(+), 1 deletion(-) diff --git a/drivers/pci/controller/pci-loongson.c b/drivers/pci/controller/pci-loongson.c index b249f46739ba..d91d1c130374 100644 --- a/drivers/pci/controller/pci-loongson.c +++ b/drivers/pci/controller/pci-loongson.c @@ -83,6 +83,26 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON, DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON, DEV_PCIE_PORT_2, loongson_mrrs_quirk); +static void loongson_bmaster_quirk(struct pci_dev *pdev) +{ + /* + * Some Loongson PCIe ports will cause CPU deadlock if disable + * the Bus Master bit during poweroff/reboot. + */ + struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus); + + if (!bridge) + return; + + bridge->no_dis_bmaster = 1; +} +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON, + DEV_PCIE_PORT_0, loongson_bmaster_quirk); +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON, + DEV_PCIE_PORT_1, loongson_bmaster_quirk); +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON, + DEV_PCIE_PORT_2, loongson_bmaster_quirk); + static struct loongson_pci *pci_bus_to_loongson_pci(struct pci_bus *bus) { struct pci_config_window *cfg; diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c index e1fed6649c41..7f9549a1f48b 100644 --- a/drivers/pci/pcie/portdrv_core.c +++ b/drivers/pci/pcie/portdrv_core.c @@ -486,9 +486,13 @@ EXPORT_SYMBOL_GPL(pcie_port_find_device); */ void pcie_port_device_remove(struct pci_dev *dev) { + struct pci_host_bridge *bridge = pci_find_host_bridge(dev->bus); + device_for_each_child(&dev->dev, NULL, remove_iter); pci_free_irq_vectors(dev); - pci_disable_device(dev); + + if (!bridge->no_dis_bmaster) + pci_disable_device(dev); } /** diff --git a/include/linux/pci.h b/include/linux/pci.h index e2583c2785e2..46dfbb61f2f0 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -542,6 +542,7 @@ struct pci_host_bridge { unsigned int ignore_reset_delay:1; /* For entire hierarchy */ unsigned int no_ext_tags:1; /* No Extended Tags */ unsigned int no_inc_mrrs:1; /* No Increase MRRS */ + unsigned int no_dis_bmaster:1; /* No Disable Bus Master */ unsigned int native_aer:1; /* OS may use PCIe AER */ unsigned int native_pcie_hotplug:1; /* OS may use PCIe hotplug */ unsigned int native_shpc_hotplug:1; /* OS may use SHPC hotplug */