https://bugzilla.kernel.org/show_bug.cgi?id=60561
Bug ID: 60561
Summary: Regression of "ACPI: Rework acpi_get_child() to be
more efficient"
Product: ACPI
Version: 2.5
Kernel Version: 3.8.5, all versions with 33f767d7
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: Power-Video
Assignee: [email protected]
Reporter: [email protected]
Regression: No
Created attachment 106894
--> https://bugzilla.kernel.org/attachment.cgi?id=106894&action=edit
acpidump for Notebook P15SM
Bug https://bugzilla.kernel.org/show_bug.cgi?id=42696 fixes incorrect
enumeration of an ACPI handle for a PCI device:
commit 33f767d767e9a684e9cd60704d4c049a2014c8d5
Author: Rafael J. Wysocki <[email protected]>
Date: Thu Jan 10 13:13:49 2013 +0100
ACPI: Rework acpi_get_child() to be more efficient
This resulted in breakage on another machine as reported here[1]. The video
card can again not be found. This seems to be caused by a Device which does not
have anything useful as shown in [2]. When the above commit is reverted (on top
of 3.9.9 and 3.10.0), the bug is gone for these users.
Details from DMI:
system-manufacturer : Notebook
system-product-name : P15SM
system-version : Not Applicable
baseboard-manufacturer: Notebook
baseboard-product-name: P15SM
baseboard-version : Not Applicable
bios-vendor : American Megatrends Inc.
bios-version : 4.6.5
bios-release-date : 04/09/2013
For some debugging attempts, see [1]. The bug occurs because the wrong ACPI
handle is attached to the PCIe Root Port. The correct handle is \_SB.PCI0.PEG0
(which has a child PEGP video device), but after the above commit it becomes
\_SB.PCI0.P0P2 (which has no children).
I thought that the commit in 3.11 that tests _STA would solve this issue (as
the P0P2 device does not have such a method), but the results were negative.
The commit they tried to apply (without revert) was:
commit c7d9ca90aa9497f0b6e301ec67c52dd4b57a7852
Author: Jeff Wu <[email protected]>
Date: Wed May 29 06:31:30 2013 +0000
ACPI: add _STA evaluation at do_acpi_find_child()
[1]: https://github.com/Bumblebee-Project/bbswitch/issues/65
[2]:
https://github.com/Bumblebee-Project/bbswitch/issues/65#issuecomment-20824596
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