From 299fad4133677b845ce962f78c9cf75bded63f61 Mon Sep 17 00:00:00 2001 From: Mario Limonciello Date: Mon, 8 Sep 2025 22:19:15 -0500 Subject: [PATCH 1/2] PCI/PM: Skip resuming to D0 if device is disconnected MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When a device is surprise-removed (e.g., due to a dock unplug), the PCI core unconfigures all downstream devices and sets their error state to pci_channel_io_perm_failure. This marks them as disconnected via pci_dev_is_disconnected(). During device removal, the runtime PM framework may attempt to resume the device to D0 via pm_runtime_get_sync(), which calls into pci_power_up(). Since the device is already disconnected, this resume attempt is unnecessary and results in a predictable errors like this, typically when undocking from a TBT3 or USB4 dock with PCIe tunneling: pci 0000:01:00.0: Unable to change power state from D3cold to D0, device inaccessible Avoid powering up disconnected devices by checking their status early in pci_power_up() and returning -EIO. Suggested-by: Lukas Wunner Signed-off-by: Mario Limonciello [bhelgaas: add typical message] Signed-off-by: Bjorn Helgaas Reviewed-by: Lukas Wunner Reviewed-by: Ilpo Järvinen Acked-by: Rafael J. Wysocki Link: https://patch.msgid.link/20250909031916.4143121-1-superm1@kernel.org --- drivers/pci/pci.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b0f4d98036cd..036511f5b262 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1374,6 +1374,11 @@ int pci_power_up(struct pci_dev *dev) return -EIO; } + if (pci_dev_is_disconnected(dev)) { + dev->current_state = PCI_D3cold; + return -EIO; + } + pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); if (PCI_POSSIBLE_ERROR(pmcsr)) { pci_err(dev, "Unable to change power state from %s to D0, device inaccessible\n", From 48991e4935078b05f80616c75d1ee2ea3ae18e58 Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Wed, 24 Sep 2025 09:57:11 -0700 Subject: [PATCH 2/2] PCI/sysfs: Ensure devices are powered for config reads The "max_link_width", "current_link_speed", "current_link_width", "secondary_bus_number", and "subordinate_bus_number" sysfs files all access config registers, but they don't check the runtime PM state. If the device is in D3cold or a parent bridge is suspended, we may see -EINVAL, bogus values, or worse, depending on implementation details. Wrap these access in pci_config_pm_runtime_{get,put}() like most of the rest of the similar sysfs attributes. Notably, "max_link_speed" does not access config registers; it returns a cached value since d2bd39c0456b ("PCI: Store all PCIe Supported Link Speeds"). Fixes: 56c1af4606f0 ("PCI: Add sysfs max_link_speed/width, current_link_speed/width, etc") Signed-off-by: Brian Norris Signed-off-by: Brian Norris Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20250924095711.v2.1.Ibb5b6ca1e2c059e04ec53140cd98a44f2684c668@changeid --- drivers/pci/pci-sysfs.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 5eea14c1f7f5..2b231ef1dac9 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -201,8 +201,14 @@ static ssize_t max_link_width_show(struct device *dev, struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + ssize_t ret; - return sysfs_emit(buf, "%u\n", pcie_get_width_cap(pdev)); + /* We read PCI_EXP_LNKCAP, so we need the device to be accessible. */ + pci_config_pm_runtime_get(pdev); + ret = sysfs_emit(buf, "%u\n", pcie_get_width_cap(pdev)); + pci_config_pm_runtime_put(pdev); + + return ret; } static DEVICE_ATTR_RO(max_link_width); @@ -214,7 +220,10 @@ static ssize_t current_link_speed_show(struct device *dev, int err; enum pci_bus_speed speed; + pci_config_pm_runtime_get(pci_dev); err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat); + pci_config_pm_runtime_put(pci_dev); + if (err) return -EINVAL; @@ -231,7 +240,10 @@ static ssize_t current_link_width_show(struct device *dev, u16 linkstat; int err; + pci_config_pm_runtime_get(pci_dev); err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat); + pci_config_pm_runtime_put(pci_dev); + if (err) return -EINVAL; @@ -247,7 +259,10 @@ static ssize_t secondary_bus_number_show(struct device *dev, u8 sec_bus; int err; + pci_config_pm_runtime_get(pci_dev); err = pci_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus); + pci_config_pm_runtime_put(pci_dev); + if (err) return -EINVAL; @@ -263,7 +278,10 @@ static ssize_t subordinate_bus_number_show(struct device *dev, u8 sub_bus; int err; + pci_config_pm_runtime_get(pci_dev); err = pci_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus); + pci_config_pm_runtime_put(pci_dev); + if (err) return -EINVAL;