Hello! PCIe card can be reset via in-band Hot Reset signal which can be triggered by PCIe bridge via Secondary Bus Reset bit in PCI config space. Kernel already exports sysfs node "reset" for triggering Functional Reset of particular function of PCI device. But in some cases Functional Reset is not enough and Hot Reset is required. Following RFC patch exports sysfs node "reset_bus" for PCI bridges which triggers Secondary Bus Reset and therefore for PCIe bridges it resets connected PCIe card. What do you think about it? Currently there is userspace script which can trigger PCIe Hot Reset by modifying PCI config space from userspace: https://alexforencich.com/wiki/en/pcie/hot-reset-linux But because kernel already provides way how to trigger Functional Reset it could provide also way how to trigger PCIe Hot Reset. diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 50fcb62d59b5..f5e11c589498 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1321,6 +1321,30 @@ static ssize_t reset_store(struct device *dev, struct device_attribute *attr, static DEVICE_ATTR(reset, 0200, NULL, reset_store); +static ssize_t reset_bus_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct pci_dev *pdev = to_pci_dev(dev); + unsigned long val; + ssize_t result = kstrtoul(buf, 0, &val); + + if (result < 0) + return result; + + if (val != 1) + return -EINVAL; + + pm_runtime_get_sync(dev); + result = pci_bridge_secondary_bus_reset(pdev); + pm_runtime_put(dev); + if (result < 0) + return result; + + return count; +} + +static DEVICE_ATTR(reset_bus, 0200, NULL, reset_bus_store); + static int pci_create_capabilities_sysfs(struct pci_dev *dev) { int retval; @@ -1332,8 +1356,15 @@ static int pci_create_capabilities_sysfs(struct pci_dev *dev) if (retval) goto error; } + if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) { + retval = device_create_file(&dev->dev, &dev_attr_reset_bus); + if (retval) + goto error_reset_bus; + } return 0; +error_reset_bus: + device_remove_file(&dev->dev, &dev_attr_reset); error: pcie_vpd_remove_sysfs_dev_files(dev); return retval; @@ -1414,6 +1445,8 @@ static void pci_remove_capabilities_sysfs(struct pci_dev *dev) device_remove_file(&dev->dev, &dev_attr_reset); dev->reset_fn = 0; } + if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) + device_remove_file(&dev->dev, &dev_attr_reset_bus); } /**
