From 4d2bc69df9fac125e2c3cc9726b1b4609c4d16c2 Mon Sep 17 00:00:00 2001 From: Stuart Hayes Date: Thu, 13 May 2021 03:03:14 +0530 Subject: [PATCH] PCI/portdrv: Enable Bandwidth Notification only if port supports it commit 00823dcbdd415c868390feaca16f0265101efab4 upstream. Previously we assumed that all Root Ports and Switch Downstream Ports supported Link Bandwidth Notification. Per spec, this is only required for Ports supporting Links wider than x1 and/or multiple Link speeds (PCIe r5.0, sec 7.5.3.6). Because we assumed all Ports supported it, we tried to set up a Bandwidth Notification IRQ, which failed for devices that don't support IRQs at all, which meant pcieport didn't attach to the Port at all. Check the Link Bandwidth Notification Capability bit and enable the service only when the Port supports it. [bhelgaas: commit log] Fixes: e8303bb7a75c ("PCI/LINK: Report degraded links via link bandwidth notification") Link: https://lore.kernel.org/r/20210512213314.7778-1-stuart.w.hayes@gmail.com Signed-off-by: Stuart Hayes Signed-off-by: Bjorn Helgaas Reviewed-by: Lukas Wunner Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/pci/pcie/portdrv_core.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c index 1b330129089f..8637f6068f9c 100644 --- a/drivers/pci/pcie/portdrv_core.c +++ b/drivers/pci/pcie/portdrv_core.c @@ -255,8 +255,13 @@ static int get_port_device_capability(struct pci_dev *dev) services |= PCIE_PORT_SERVICE_DPC; if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM || - pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) - services |= PCIE_PORT_SERVICE_BWNOTIF; + pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) { + u32 linkcap; + + pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &linkcap); + if (linkcap & PCI_EXP_LNKCAP_LBNC) + services |= PCIE_PORT_SERVICE_BWNOTIF; + } return services; }