From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753470AbeDSVFe (ORCPT ); Thu, 19 Apr 2018 17:05:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:60428 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753396AbeDSVFc (ORCPT ); Thu, 19 Apr 2018 17:05:32 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A2D12177E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=helgaas@kernel.org Subject: [PATCH v1 1/2] PCI/ASPM: Disable ASPM L1.2 Substate if we don't have LTR From: Bjorn Helgaas To: linux-pci@vger.kernel.org Cc: "Rafael J. Wysocki" , Sinan Kaya , Rajat Jain , Srinath Mannam , Ray Jui , Keith Busch , linux-acpi@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Date: Thu, 19 Apr 2018 16:05:29 -0500 Message-ID: <152417192976.76853.5171081412139699180.stgit@bhelgaas-glaptop.roam.corp.google.com> In-Reply-To: <152417080402.76853.4258398181136860884.stgit@bhelgaas-glaptop.roam.corp.google.com> References: <152417080402.76853.4258398181136860884.stgit@bhelgaas-glaptop.roam.corp.google.com> User-Agent: StGit/0.18 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bjorn Helgaas When in the ASPM L1.0 state (but not the PCI-PM L1.0 state), the most recent LTR value and the LTR_L1.2_THRESHOLD determines whether the link enters the L1.2 substate. If we don't have LTR enabled, prevent the use of ASPM L1.2. PCI-PM L1.2 may still be used because it doesn't depend on LTR_L1.2_THRESHOLD (see PCIe r4.0, sec 5.5.1). Signed-off-by: Bjorn Helgaas --- drivers/pci/pcie/aspm.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index f76eb7704f64..c687c817b47d 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -400,6 +400,15 @@ static void pcie_get_aspm_reg(struct pci_dev *pdev, info->l1ss_cap = 0; return; } + + /* + * If we don't have LTR for the entire path from the Root Complex + * to this device, we can't use ASPM L1.2 because it relies on the + * LTR_L1.2_THRESHOLD. See PCIe r4.0, secs 5.5.4, 6.18. + */ + if (!pdev->ltr_path) + info->l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2; + pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL1, &info->l1ss_ctl1); pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL2,