From patchwork Wed Oct 7 16:48:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "David E. Box" X-Patchwork-Id: 11821315 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8499114D5 for ; Wed, 7 Oct 2020 17:24:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 725342176B for ; Wed, 7 Oct 2020 17:24:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728229AbgJGRX7 (ORCPT ); Wed, 7 Oct 2020 13:23:59 -0400 Received: from mga03.intel.com ([134.134.136.65]:1354 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727969AbgJGRX7 (ORCPT ); Wed, 7 Oct 2020 13:23:59 -0400 IronPort-SDR: XejR/9Mbmw6bTXi00mTdvFcXXvW7H7Iu2Lb/jKLy7d/EEPiEaBUwyU5fT62lkUjjIarNomLzrB NetAGuBRXJEg== X-IronPort-AV: E=McAfee;i="6000,8403,9767"; a="165087285" X-IronPort-AV: E=Sophos;i="5.77,347,1596524400"; d="scan'208";a="165087285" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Oct 2020 09:48:57 -0700 IronPort-SDR: JS5WF/ZWWJ6drdqE9KPrrDpGO1nBnyE4kYAX0TQWWs/O+DP5LvoNAnanbch5hAQcdmV4FDKhDy /8xYVEACsEgA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,347,1596524400"; d="scan'208";a="311818207" Received: from linux.intel.com ([10.54.29.200]) by orsmga003.jf.intel.com with ESMTP; 07 Oct 2020 09:48:56 -0700 Received: from debox1-desk2.jf.intel.com (debox1-desk2.jf.intel.com [10.54.75.16]) by linux.intel.com (Postfix) with ESMTP id 01586580867; Wed, 7 Oct 2020 09:48:56 -0700 (PDT) From: "David E. Box" To: bhelgaas@google.com, len.brown@intel.com, rafael@kernel.org Cc: "David E. Box" , linux-pci@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] PCI: Disable PTM during suspend on Intel PCI bridges Date: Wed, 7 Oct 2020 09:48:51 -0700 Message-Id: <20201007164851.1218-1-david.e.box@linux.intel.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Intel Platform Controller Hubs (PCH) since Cannon Lake, the Precision Time Measurement (PTM) capability can prevent PCIe root ports from power gating during suspend-to-idle, causing increased power consumption on systems that suspend using Low Power S0 Idle [1]. The issue is yet to be root caused but believed to be coming from a race condition in the suspend flow as the incidence rate varies for different platforms on Linux but the issue does not occur at all in other operating systems. For now, disable the feature on suspend on all Intel root ports and enable again on resume. Link: https://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf Bug: https://bugzilla.kernel.org/show_bug.cgi?id=209361 Tested-by: Len Brown Signed-off-by: David E. Box --- drivers/pci/quirks.c | 57 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index bdf9b52567e0..e82b1f60c7a1 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -5632,3 +5632,60 @@ static void apex_pci_fixup_class(struct pci_dev *pdev) } DECLARE_PCI_FIXUP_CLASS_HEADER(0x1ac1, 0x089a, PCI_CLASS_NOT_DEFINED, 8, apex_pci_fixup_class); + +#ifdef CONFIG_PCIE_PTM +/* + * On Intel Platform Controller Hubs (PCH) since Cannon Lake, the Precision + * Time Measurement (PTM) capability can prevent the PCIe root port from + * power gating during suspend-to-idle, causing increased power consumption. + * So disable the feature on suspend on all Intel root ports and enable + * again on resume. + */ +static void quirk_intel_ptm_disable_suspend(struct pci_dev *dev) +{ + int pos; + u32 ctrl; + + if (!(dev->ptm_enabled && dev->ptm_root)) + return; + + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); + if (!pos) + return; + + pci_dbg(dev, "quirk: disabling PTM\n"); + + dev->ptm_enabled = 0; + dev->ptm_root = 0; + + pci_read_config_dword(dev, pos + PCI_PTM_CTRL, &ctrl); + ctrl &= ~(PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT); + pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl); +} + +static void quirk_intel_ptm_enable_resume(struct pci_dev *dev) +{ + int pos; + u32 ctrl; + + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); + if (!pos) + return; + + pci_dbg(dev, "quirk: re-enabling PTM\n"); + + pci_read_config_dword(dev, pos + PCI_PTM_CTRL, &ctrl); + ctrl |= PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT; + pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl); + + dev->ptm_enabled = 1; + dev->ptm_root = 1; +} + +DECLARE_PCI_FIXUP_CLASS_SUSPEND(PCI_VENDOR_ID_INTEL, PCI_ANY_ID, + PCI_CLASS_BRIDGE_PCI, 8, + quirk_intel_ptm_disable_suspend) +DECLARE_PCI_FIXUP_CLASS_RESUME(PCI_VENDOR_ID_INTEL, PCI_ANY_ID, + PCI_CLASS_BRIDGE_PCI, 8, + quirk_intel_ptm_enable_resume) +#endif