From patchwork Tue Feb 2 20:50:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bjorn Helgaas X-Patchwork-Id: 1434936 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=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=RN2yaenZ; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4DVcRd3llZz9tjs for ; Wed, 3 Feb 2021 07:51:25 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233199AbhBBUvI (ORCPT ); Tue, 2 Feb 2021 15:51:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:41656 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231193AbhBBUvF (ORCPT ); Tue, 2 Feb 2021 15:51:05 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id EFEA364E38; Tue, 2 Feb 2021 20:50:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612299022; bh=KAMQGQO1pfD3t34LGdFZWhK0tJH4obaQlEHMOr9wuhw=; h=From:To:Cc:Subject:Date:From; b=RN2yaenZ+37TyzEarkMHGxUHB5hwOOEUQzn9/b/0xDmf/d/EQ2CLeNm5YcZEEJV0j JCIXPkSPuV1iaIvHfu7GHG2M9Ip9NdaoMqnv1DlUj4RF9gnbHXdWNY0t6oGqR1TxW0 MTtiRo8hzES0DD/2SaEyyFpobmjaibzv43OC9LtkSlc6Z8U0aHMltpO1QZkhl/FP96 JmUB61TVhd0FQsUMhamdMNab+VS3oj3wcJVtinRLFYtobR8FgFL3XrnAh8q9rE2CcM ia48HLbQbH0BMBq3wl07KHNWU23W20PjOSNzg3E+SXxzen6QrPD0rSme4VtzYnQQMr KilykHiVZUpow== From: Bjorn Helgaas To: linux-pci@vger.kernel.org Cc: Alex Gagniuc , Sinan Kaya , Keith Busch , Jan Vesely , Lukas Wunner , Alex Williamson , Austin Bolen , Shyam Iyer , Christoph Hellwig , Lucas Stach , Dave Airlie , Ben Skeggs , Alex Deucher , Myron Stowe , "A . Vladimirov" , linux-kernel@vger.kernel.org, Bjorn Helgaas Subject: [PATCH] PCI/LINK: Remove bandwidth notification Date: Tue, 2 Feb 2021 14:50:13 -0600 Message-Id: <20210202205014.136880-1-helgaas@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Bjorn Helgaas The PCIe Bandwidth Change Notification feature logs messages when the link bandwidth changes. Some users have reported that these messages occur often enough to significantly reduce NVMe performance. GPUs also seem to generate these messages. We don't know why the link bandwidth changes, but in the reported cases there's no indication that it's caused by hardware failures. Remove the bandwidth change notifications for now. Hopefully we can add this back when we have a better understanding of why this happens and how we can make the messages useful instead of overwhelming. Link: https://lore.kernel.org/r/20200115221008.GA191037@google.com/ Link: https://lore.kernel.org/r/155605909349.3575.13433421148215616375.stgit@gimli.home/ Link: https://bugzilla.kernel.org/show_bug.cgi?id=206197 Signed-off-by: Bjorn Helgaas --- drivers/pci/pcie/Kconfig | 8 -- drivers/pci/pcie/Makefile | 1 - drivers/pci/pcie/bw_notification.c | 138 ----------------------------- drivers/pci/pcie/portdrv.h | 6 -- drivers/pci/pcie/portdrv_pci.c | 1 - 5 files changed, 154 deletions(-) delete mode 100644 drivers/pci/pcie/bw_notification.c diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig index 3946555a6042..45a2ef702b45 100644 --- a/drivers/pci/pcie/Kconfig +++ b/drivers/pci/pcie/Kconfig @@ -133,14 +133,6 @@ config PCIE_PTM This is only useful if you have devices that support PTM, but it is safe to enable even if you don't. -config PCIE_BW - bool "PCI Express Bandwidth Change Notification" - depends on PCIEPORTBUS - help - This enables PCI Express Bandwidth Change Notification. If - you know link width or rate changes occur only to correct - unreliable links, you may answer Y. - config PCIE_EDR bool "PCI Express Error Disconnect Recover support" depends on PCIE_DPC && ACPI diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile index d9697892fa3e..b2980db88cc0 100644 --- a/drivers/pci/pcie/Makefile +++ b/drivers/pci/pcie/Makefile @@ -12,5 +12,4 @@ obj-$(CONFIG_PCIEAER_INJECT) += aer_inject.o obj-$(CONFIG_PCIE_PME) += pme.o obj-$(CONFIG_PCIE_DPC) += dpc.o obj-$(CONFIG_PCIE_PTM) += ptm.o -obj-$(CONFIG_PCIE_BW) += bw_notification.o obj-$(CONFIG_PCIE_EDR) += edr.o diff --git a/drivers/pci/pcie/bw_notification.c b/drivers/pci/pcie/bw_notification.c deleted file mode 100644 index 565d23cccb8b..000000000000 --- a/drivers/pci/pcie/bw_notification.c +++ /dev/null @@ -1,138 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0+ -/* - * PCI Express Link Bandwidth Notification services driver - * Author: Alexandru Gagniuc - * - * Copyright (C) 2019, Dell Inc - * - * The PCIe Link Bandwidth Notification provides a way to notify the - * operating system when the link width or data rate changes. This - * capability is required for all root ports and downstream ports - * supporting links wider than x1 and/or multiple link speeds. - * - * This service port driver hooks into the bandwidth notification interrupt - * and warns when links become degraded in operation. - */ - -#define dev_fmt(fmt) "bw_notification: " fmt - -#include "../pci.h" -#include "portdrv.h" - -static bool pcie_link_bandwidth_notification_supported(struct pci_dev *dev) -{ - int ret; - u32 lnk_cap; - - ret = pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnk_cap); - return (ret == PCIBIOS_SUCCESSFUL) && (lnk_cap & PCI_EXP_LNKCAP_LBNC); -} - -static void pcie_enable_link_bandwidth_notification(struct pci_dev *dev) -{ - u16 lnk_ctl; - - pcie_capability_write_word(dev, PCI_EXP_LNKSTA, PCI_EXP_LNKSTA_LBMS); - - pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &lnk_ctl); - lnk_ctl |= PCI_EXP_LNKCTL_LBMIE; - pcie_capability_write_word(dev, PCI_EXP_LNKCTL, lnk_ctl); -} - -static void pcie_disable_link_bandwidth_notification(struct pci_dev *dev) -{ - u16 lnk_ctl; - - pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &lnk_ctl); - lnk_ctl &= ~PCI_EXP_LNKCTL_LBMIE; - pcie_capability_write_word(dev, PCI_EXP_LNKCTL, lnk_ctl); -} - -static irqreturn_t pcie_bw_notification_irq(int irq, void *context) -{ - struct pcie_device *srv = context; - struct pci_dev *port = srv->port; - u16 link_status, events; - int ret; - - ret = pcie_capability_read_word(port, PCI_EXP_LNKSTA, &link_status); - events = link_status & PCI_EXP_LNKSTA_LBMS; - - if (ret != PCIBIOS_SUCCESSFUL || !events) - return IRQ_NONE; - - pcie_capability_write_word(port, PCI_EXP_LNKSTA, events); - pcie_update_link_speed(port->subordinate, link_status); - return IRQ_WAKE_THREAD; -} - -static irqreturn_t pcie_bw_notification_handler(int irq, void *context) -{ - struct pcie_device *srv = context; - struct pci_dev *port = srv->port; - struct pci_dev *dev; - - /* - * Print status from downstream devices, not this root port or - * downstream switch port. - */ - down_read(&pci_bus_sem); - list_for_each_entry(dev, &port->subordinate->devices, bus_list) - pcie_report_downtraining(dev); - up_read(&pci_bus_sem); - - return IRQ_HANDLED; -} - -static int pcie_bandwidth_notification_probe(struct pcie_device *srv) -{ - int ret; - - /* Single-width or single-speed ports do not have to support this. */ - if (!pcie_link_bandwidth_notification_supported(srv->port)) - return -ENODEV; - - ret = request_threaded_irq(srv->irq, pcie_bw_notification_irq, - pcie_bw_notification_handler, - IRQF_SHARED, "PCIe BW notif", srv); - if (ret) - return ret; - - pcie_enable_link_bandwidth_notification(srv->port); - pci_info(srv->port, "enabled with IRQ %d\n", srv->irq); - - return 0; -} - -static void pcie_bandwidth_notification_remove(struct pcie_device *srv) -{ - pcie_disable_link_bandwidth_notification(srv->port); - free_irq(srv->irq, srv); -} - -static int pcie_bandwidth_notification_suspend(struct pcie_device *srv) -{ - pcie_disable_link_bandwidth_notification(srv->port); - return 0; -} - -static int pcie_bandwidth_notification_resume(struct pcie_device *srv) -{ - pcie_enable_link_bandwidth_notification(srv->port); - return 0; -} - -static struct pcie_port_service_driver pcie_bandwidth_notification_driver = { - .name = "pcie_bw_notification", - .port_type = PCIE_ANY_PORT, - .service = PCIE_PORT_SERVICE_BWNOTIF, - .probe = pcie_bandwidth_notification_probe, - .suspend = pcie_bandwidth_notification_suspend, - .resume = pcie_bandwidth_notification_resume, - .remove = pcie_bandwidth_notification_remove, -}; - -int __init pcie_bandwidth_notification_init(void) -{ - return pcie_port_service_register(&pcie_bandwidth_notification_driver); -} diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h index af7cf237432a..2ff5724b8f13 100644 --- a/drivers/pci/pcie/portdrv.h +++ b/drivers/pci/pcie/portdrv.h @@ -53,12 +53,6 @@ int pcie_dpc_init(void); static inline int pcie_dpc_init(void) { return 0; } #endif -#ifdef CONFIG_PCIE_BW -int pcie_bandwidth_notification_init(void); -#else -static inline int pcie_bandwidth_notification_init(void) { return 0; } -#endif - /* Port Type */ #define PCIE_ANY_PORT (~0) diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c index 0b250bc5f405..8bd4992a4f32 100644 --- a/drivers/pci/pcie/portdrv_pci.c +++ b/drivers/pci/pcie/portdrv_pci.c @@ -255,7 +255,6 @@ static void __init pcie_init_services(void) pcie_pme_init(); pcie_dpc_init(); pcie_hp_init(); - pcie_bandwidth_notification_init(); } static int __init pcie_portdrv_init(void)