Patch "ACPI / scan: Prefer devices without _HID for _ADR matching" has been added to the 4.10-stable tree

This is a note to let you know that I've just added the patch titled

ACPI / scan: Prefer devices without _HID for _ADR matching

to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
acpi-scan-prefer-devices-without-_hid-for-_adr-matching.patch
and it can be found in the queue-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Rafael J. Wysocki" <[email protected]>
Date: Sat, 1 Apr 2017 00:45:52 +0200
Subject: ACPI / scan: Prefer devices without _HID for _ADR matching

From: Rafael J. Wysocki <[email protected]>

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).

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

@@ -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;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.10/acpi-scan-prefer-devices-without-_hid-for-_adr-matching.patch