From 285f1726f983c5ebce4a6d6e7b5ead31bd08ab88 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Fri, 15 Mar 2019 10:29:15 +0800 Subject: [PATCH] PCI/ASPM: Use LTR if already enabled by platform mainline inclusion from mainline-5.0 commit 10ecc818ea73 category: bugfix bugzilla: 12109 CVE: NA ------------------------------------------------- RussianNeuroMancer reported that the Intel 7265 wifi on a Dell Venue 11 Pro 7140 table stopped working after wakeup from suspend and bisected the problem to 9ab105deb60f ("PCI/ASPM: Disable ASPM L1.2 Substate if we don't have LTR"). David Ward reported the same problem on a Dell Latitude 7350. After af8bb9f89838 ("PCI/ACPI: Request LTR control from platform before using it"), we don't enable LTR unless the platform has granted LTR control to us. In addition, we don't notice if the platform had already enabled LTR itself. After 9ab105deb60f ("PCI/ASPM: Disable ASPM L1.2 Substate if we don't have LTR"), we avoid using LTR if we don't think the path to the device has LTR enabled. The combination means that if the platform itself enables LTR but declines to give the OS control over LTR, we unnecessarily avoided using ASPM L1.2. Link: https://bugzilla.kernel.org/show_bug.cgi?id=201469 Fixes: 9ab105deb60f ("PCI/ASPM: Disable ASPM L1.2 Substate if we don't have LTR") Fixes: af8bb9f89838 ("PCI/ACPI: Request LTR control from platform before using it") Reported-by: RussianNeuroMancer Reported-by: David Ward Signed-off-by: Bjorn Helgaas CC: stable@vger.kernel.org # v4.18+ Signed-off-by: Xiongfeng Wang Reviewed-by: Yao Hongbo Signed-off-by: Yang Yingliang --- drivers/pci/probe.c | 36 +++++++++++++++++++++++------------- 1 file changed, 23 insertions(+), 13 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 864d471bbe97..6c06fa59e733 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2090,11 +2090,8 @@ static void pci_configure_ltr(struct pci_dev *dev) { #ifdef CONFIG_PCIEASPM struct pci_host_bridge *host = pci_find_host_bridge(dev->bus); - u32 cap; struct pci_dev *bridge; - - if (!host->native_ltr) - return; + u32 cap, ctl; if (!pci_is_pcie(dev)) return; @@ -2103,22 +2100,35 @@ static void pci_configure_ltr(struct pci_dev *dev) if (!(cap & PCI_EXP_DEVCAP2_LTR)) return; - /* - * Software must not enable LTR in an Endpoint unless the Root - * Complex and all intermediate Switches indicate support for LTR. - * PCIe r3.1, sec 6.18. - */ - if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) - dev->ltr_path = 1; - else { + pcie_capability_read_dword(dev, PCI_EXP_DEVCTL2, &ctl); + if (ctl & PCI_EXP_DEVCTL2_LTR_EN) { + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) { + dev->ltr_path = 1; + return; + } + bridge = pci_upstream_bridge(dev); if (bridge && bridge->ltr_path) dev->ltr_path = 1; + + return; } - if (dev->ltr_path) + if (!host->native_ltr) + return; + + /* + * Software must not enable LTR in an Endpoint unless the Root + * Complex and all intermediate Switches indicate support for LTR. + * PCIe r4.0, sec 6.18. + */ + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT || + ((bridge = pci_upstream_bridge(dev)) && + bridge->ltr_path)) { pcie_capability_set_word(dev, PCI_EXP_DEVCTL2, PCI_EXP_DEVCTL2_LTR_EN); + dev->ltr_path = 1; + } #endif } -- GitLab