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>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/pnp/pnpacpi/core.c b/drivers/pnp/pnpacpi/core.c
index c1b9ea34977b..98b9df7776e9 100644
--- a/drivers/pnp/pnpacpi/core.c
+++ b/drivers/pnp/pnpacpi/core.c
@@ -148,9 +148,13 @@ static int __init pnpacpi_add_device(struct acpi_device *device)
 	acpi_status status;
 	struct pnp_dev *dev;
 
+	/*
+	 * If a PnPacpi device is not present , the device
+	 * driver should not be loaded.
+	 */
 	status = acpi_get_handle(device->handle, "_CRS", &temp);
 	if (ACPI_FAILURE(status) || !ispnpidacpi(acpi_device_hid(device)) ||
-	    is_exclusive_device(device))
+	    is_exclusive_device(device) || (!device->status.present))
 		return 0;
 
 	dev = pnp_alloc_dev(&pnpacpi_protocol, num, acpi_device_hid(device));