[PATCH 4.10 026/110] ACPI / scan: Prefer devices without _HID for _ADR matching

[Greg Kroah-Hartman]

4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

commit fdad4e7a876a2cb3d2c1f04e5418c324e79fffef upstream.

Commit c2a6bbaf0c5f (ACPI / scan: Prefer devices without _HID/_CID
for _ADR matching) added a list_empty(&adev->pnp.ids) check to
find_child_checks() so as to catch situations in which the ACPI
core attempts to decode _ADR for a device having a _HID too which
is strictly against the spec.  However, it overlooked the fact that
the adev->pnp.ids list for the devices taken into account by
find_child_checks() may contain device IDs set internally by the
kernel, like "LNXVIDEO" (thanks to Zhang Rui for that realization),
and it broke the enumeration of those devices as a result.

To unbreak it, replace the overly coarse grained list_empty()
check with a much more precise check against the pnp.type.platform_id
flag which is only set for devices having a _HID (that's how it
should be done from the start, as having both _ADR and _CID is
actually permitted).

Fixes: c2a6bbaf0c5f (ACPI / scan: Prefer devices without _HID/_CID for _ADR matching)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=194889
Reported-and-tested-by: Mike <mike@xxxxxxxxxxxxxxxx>
Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/acpi/glue.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -99,13 +99,13 @@ static int find_child_checks(struct acpi
 		return -ENODEV;
 
 	/*
-	 * If the device has a _HID (or _CID) returning a valid ACPI/PNP
-	 * device ID, it is better to make it look less attractive here, so that
-	 * the other device with the same _ADR value (that may not have a valid
-	 * device ID) can be matched going forward.  [This means a second spec
-	 * violation in a row, so whatever we do here is best effort anyway.]
+	 * If the device has a _HID returning a valid ACPI/PNP device ID, it is
+	 * better to make it look less attractive here, so that the other device
+	 * with the same _ADR value (that may not have a valid device ID) can be
+	 * matched going forward.  [This means a second spec violation in a row,
+	 * so whatever we do here is best effort anyway.]
 	 */
-	return sta_present && list_empty(&adev->pnp.ids) ?
+	return sta_present && !adev->pnp.type.platform_id ?
 			FIND_CHILD_MAX_SCORE : FIND_CHILD_MIN_SCORE;
 }