ACPI : Load device driver according to the status of acpi device
According to ACPI spec when the status of some device is not present
but functional, the device is valid and the children of this device
should be enumerated. It means that the device should be added to
linux acpi device tree. But the device driver for this device should not
be loaded.
The detailed info can be found in the section 6.3.7 of ACPI 3.0b spec.
_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. OS should continue
enumeration below a device whose _STA returns this bit combination
http://bugzilla.kernel.org/show_bug.cgi?id=3358
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Li Shaohua <shaohua.li@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index ad06798..89c112e 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -276,6 +276,13 @@
{
const struct acpi_device_id *id;
+ /*
+ * If the device is not present, it is unnecessary to load device
+ * driver for it.
+ */
+ if (!device->status.present)
+ return -ENODEV;
+
if (device->flags.hardware_id) {
for (id = ids; id->id[0]; id++) {
if (!strcmp((char*)id->id, device->pnp.hardware_id))
@@ -1222,15 +1229,18 @@
result = -ENODEV;
goto end;
}
- if (!device->status.present) {
- /* Bay and dock should be handled even if absent */
- if (!ACPI_SUCCESS(
- acpi_is_child_device(device, acpi_bay_match)) &&
- !ACPI_SUCCESS(
- acpi_is_child_device(device, acpi_dock_match))) {
- result = -ENODEV;
- goto end;
- }
+ /*
+ * When the device is neither present nor functional, the
+ * device should not be added to Linux ACPI device tree.
+ * When the status of the device is not present but functinal,
+ * it should be added to Linux ACPI tree. For example : bay
+ * device , dock device.
+ * In such conditions it is unncessary to check whether it is
+ * bay device or dock device.
+ */
+ if (!device->status.present && !device->status.functional) {
+ result = -ENODEV;
+ goto end;
}
break;
default:
@@ -1411,7 +1421,12 @@
* TBD: Need notifications and other detection mechanisms
* in place before we can fully implement this.
*/
- if (child->status.present) {
+ /*
+ * When the device is not present but functional, it is also
+ * necessary to scan the children of this device.
+ */
+ if (child->status.present || (!child->status.present &&
+ child->status.functional)) {
status = acpi_get_next_object(ACPI_TYPE_ANY, chandle,
NULL, NULL);
if (ACPI_SUCCESS(status)) {