From 7282059489868e0ed1b0d79765730c6b233a8399 Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Tue, 11 Feb 2014 12:42:37 +0200 Subject: ACPI / hotplug / PCI: Relax the checking of _STA return values The ACPI specification (ACPI 5.0A, Section 6.3.7) says: _STA may return bit 0 clear (not present) with bit 3 set (device is functional). This case is used to indicate a valid device for which no device driver should be loaded (for example, a bridge device.) Children of this device may be present and valid. OSPM should continue enumeration below a device whose _STA returns this bit combination. Evidently, some BIOSes follow that and return 0x0A from _STA, which causes problems to happen when they trigger bus check or device check notifications for those devices too. Namely, ACPIPHP thinks that they are gone and may drop them, for example, if such a notification is triggered during a resume from system suspend. To fix that, modify ACPICA to regard devies as present and functioning if _STA returns both the ACPI_STA_DEVICE_ENABLED and ACPI_STA_DEVICE_FUNCTIONING bits set for them. Reported-and-tested-by: Peter Wu Cc: 3.12+ # 3.12+ [rjw: Subject and changelog, minor code modifications] Signed-off-by: Rafael J. Wysocki --- drivers/pci/hotplug/acpiphp_glue.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index e2a783fdb98f..7c7a388c85ab 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -730,6 +730,17 @@ static unsigned int get_slot_status(struct acpiphp_slot *slot) return (unsigned int)sta; } +static inline bool device_status_valid(unsigned int sta) +{ + /* + * ACPI spec says that _STA may return bit 0 clear with bit 3 set + * if the device is valid but does not require a device driver to be + * loaded (Section 6.3.7 of ACPI 5.0A). + */ + unsigned int mask = ACPI_STA_DEVICE_ENABLED | ACPI_STA_DEVICE_FUNCTIONING; + return (sta & mask) == mask; +} + /** * trim_stale_devices - remove PCI devices that are not responding. * @dev: PCI device to start walking the hierarchy from. @@ -745,7 +756,7 @@ static void trim_stale_devices(struct pci_dev *dev) unsigned long long sta; status = acpi_evaluate_integer(handle, "_STA", NULL, &sta); - alive = (ACPI_SUCCESS(status) && sta == ACPI_STA_ALL) + alive = (ACPI_SUCCESS(status) && device_status_valid(sta)) || acpiphp_no_hotplug(handle); } if (!alive) { @@ -792,7 +803,7 @@ static void acpiphp_check_bridge(struct acpiphp_bridge *bridge) mutex_lock(&slot->crit_sect); if (slot_no_hotplug(slot)) { ; /* do nothing */ - } else if (get_slot_status(slot) == ACPI_STA_ALL) { + } else if (device_status_valid(get_slot_status(slot))) { /* remove stale devices if any */ list_for_each_entry_safe_reverse(dev, tmp, &bus->devices, bus_list) -- cgit v1.2.3