From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> As the kernel Bugzilla report #42696 indicates, it generally is not sufficient to use _ADR to get an ACPI device node corresponding to the given PCI device, because there may be multiple objects with matching _ADR in the ACPI namespace (this probably is against the spec, but it evidently happens in practice). One possible way to improve the situation is to use the presence of another ACPI method to distinguish between the matching namespace nodes. For example, if the presence of _INI is checked in addition to the return value of _ADR, bug #42696 goes away on the affected machines. Of course, this is somewhat arbitrary, but it may be argued that executing _INI for an ACPI device node kind of means that we are going to use that device node going forward, so we should generally prefer the nodes where we have executed _INI to "competing" nodes without _INI. In that case, though, we shouldn't take the nodes where we haven't executed _INI into account, but that's quite straightforwad to achieve. Namely, we only need to check nodes that we created struct acpi_device objects for. This also makes sense for a different reason, which is that the result of acpi_pci_find_device() is used to get a struct acpi_device object (not just an ACPI handle) corresponding to the given PCI device. Accordingly, introduce acpi_get_child_device() that finds a struct acpi_device corresponding to the given address by walking the children of the ACPI device node whose handle is its first argument. The lookup is carried out by evaluating _ADR for every child and comparing the result with the given address. If there's a match and that child has _INI defined, it is returned as a result. If _INI is not present, the search continues until (a) there are no more matches or (b) there is another matching child whose _INI is present (in which case that child is returned instead of the first matching one). The walk of the list of children is done in the reverse direction for two reasons. The first reason is for compatibility with acpi_get_child() that returns the handle of the last matching child of the given parent. The second one is to get the last device whose _INI was executed first (that _INI might have overriden whatever _INI for the other matching device nodes had done). To fix bug #42696, modify acpi_pci_find_device() to use acpi_get_child_device() instead of acpi_get_child() for ACPI device node lookup. References: https://bugzilla.kernel.org/show_bug.cgi?id=42696 Reported-by: Peter Wu <lekensteyn@xxxxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> --- drivers/acpi/glue.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ drivers/acpi/internal.h | 4 ++++ drivers/acpi/proc.c | 1 + drivers/acpi/sleep.h | 1 - drivers/pci/pci-acpi.c | 7 +++++-- include/acpi/acpi_bus.h | 1 + 6 files changed, 56 insertions(+), 3 deletions(-) Index: linux/drivers/acpi/glue.c =================================================================== --- linux.orig/drivers/acpi/glue.c +++ linux/drivers/acpi/glue.c @@ -93,6 +93,51 @@ static int acpi_find_bridge_device(struc return ret; } +/** + * acpi_get_child_device - Find specific child of an ACPI device. + * @phandle: ACPI handle of the parent device to find a child of. + * @address: Address of the child to find (as returned by _ADR). + * + * Find the child of the ACPI device node represented by @phandle whose _ADR + * method's return value is equal to @address. If there are more children with + * matching _ADR return values, take the (last) one having _INI defined. + */ +struct acpi_device *acpi_get_child_device(acpi_handle phandle, u64 address) +{ + struct acpi_device *parent, *adev, *ret = NULL; + + if (acpi_bus_get_device(phandle, &parent)) + return NULL; + + mutex_lock(&acpi_device_lock); + /* Use reverse direction for compatibility with acpi_get_child(). */ + list_for_each_entry_reverse(adev, &parent->children, node) { + unsigned long long addr; + acpi_status status; + acpi_handle out; + + status = acpi_evaluate_integer(adev->handle, METHOD_NAME__ADR, + NULL, &addr); + if (ACPI_FAILURE(status) || addr != address) + continue; + + if (ret) + acpi_handle_warn(adev->handle, + "_ADR conflict with device %s\n", + dev_name(&ret->dev)); + + status = acpi_get_handle(adev->handle, "_INI", &out); + if (ACPI_SUCCESS(status)) { + ret = adev; + break; + } else if (!ret) { + ret = adev; + } + } + mutex_unlock(&acpi_device_lock); + return ret; +} + /* Get device's handler per its address under its parent */ struct acpi_find_child { acpi_handle handle; Index: linux/drivers/acpi/internal.h =================================================================== --- linux.orig/drivers/acpi/internal.h +++ linux/drivers/acpi/internal.h @@ -21,8 +21,12 @@ #ifndef _ACPI_INTERNAL_H_ #define _ACPI_INTERNAL_H_ +#include <linux/mutex.h> + #define PREFIX "ACPI: " +extern struct mutex acpi_device_lock; + int init_acpi_device_notify(void); int acpi_scan_init(void); int acpi_sysfs_init(void); Index: linux/drivers/acpi/sleep.h =================================================================== --- linux.orig/drivers/acpi/sleep.h +++ linux/drivers/acpi/sleep.h @@ -5,4 +5,3 @@ extern void acpi_enable_wakeup_devices(u extern void acpi_disable_wakeup_devices(u8 sleep_state); extern struct list_head acpi_wakeup_device_list; -extern struct mutex acpi_device_lock; Index: linux/drivers/acpi/proc.c =================================================================== --- linux.orig/drivers/acpi/proc.c +++ linux/drivers/acpi/proc.c @@ -12,6 +12,7 @@ #include <linux/mc146818rtc.h> #endif +#include "internal.h" #include "sleep.h" #define _COMPONENT ACPI_SYSTEM_COMPONENT Index: linux/include/acpi/acpi_bus.h =================================================================== --- linux.orig/include/acpi/acpi_bus.h +++ linux/include/acpi/acpi_bus.h @@ -400,6 +400,7 @@ struct acpi_pci_root { }; /* helper */ +struct acpi_device *acpi_get_child_device(acpi_handle phandle, u64 address); acpi_handle acpi_get_child(acpi_handle, u64); int acpi_is_root_bridge(acpi_handle); struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle); Index: linux/drivers/pci/pci-acpi.c =================================================================== --- linux.orig/drivers/pci/pci-acpi.c +++ linux/drivers/pci/pci-acpi.c @@ -291,14 +291,17 @@ static struct pci_platform_pm_ops acpi_p static int acpi_pci_find_device(struct device *dev, acpi_handle *handle) { struct pci_dev * pci_dev; + struct acpi_device *adev; u64 addr; pci_dev = to_pci_dev(dev); /* Please ref to ACPI spec for the syntax of _ADR */ addr = (PCI_SLOT(pci_dev->devfn) << 16) | PCI_FUNC(pci_dev->devfn); - *handle = acpi_get_child(DEVICE_ACPI_HANDLE(dev->parent), addr); - if (!*handle) + adev = acpi_get_child_device(ACPI_HANDLE(dev->parent), addr); + if (!adev) return -ENODEV; + + *handle = adev->handle; return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
