From: Stuart Hayes stuart.w.hayes@gmail.com
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 stuart.w.hayes@gmail.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Lukas Wunner lukas@wunner.de Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/pcie/portdrv_core.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/drivers/pci/pcie/portdrv_core.c +++ b/drivers/pci/pcie/portdrv_core.c @@ -255,8 +255,13 @@ static int get_port_device_capability(st 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; }