ACPI: make sure every acpi_device has an ID

This makes sure every acpi_device has at least one ID.  If we build an
acpi_device for a namespace node with no _HID or _CID, we sometimes
synthesize an ID like "LNXCPU" or "LNXVIDEO".  If we don't even have
that, give it a default "device" ID.

Note that this means things like:
    /sys/devices/LNXSYSTM:00/LNXSYBUS:00/HWP0001:00/HWP0002:04/device:00
(a PCI slot SxFy device) will have "hid" and "modprobe" entries, where
they didn't before.  These aren't very useful (a HID of "device" doesn't
tell you what *kind* of device it is, so it doesn't help find a driver),
but I don't think they're harmful.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 269c0aae4bed..53b96e7a64ab 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1155,6 +1155,16 @@ static void acpi_device_set_id(struct acpi_device *device)
                 break;
         }
 
+        /*
+         * We build acpi_devices for some objects that don't have _HID or _CID,
+         * e.g., PCI bridges and slots.  Drivers can't bind to these objects,
+         * but we do use them indirectly by traversing the acpi_device tree.
+         * This generic ID isn't useful for driver binding, but it provides
+         * the useful property that "every acpi_device has an ID."
+         */
+        if (!hid && !cid_list && !cid_add)
+                hid = "device";
+
         if (hid) {
                 device->pnp.hardware_id = ACPI_ALLOCATE_ZEROED(strlen (hid) + 1);
                 if (device->pnp.hardware_id) {