Bug 16599

Summary: ACPI brightness control misses _BQC function
Product: ACPI Reporter: Jonathan Dray (jonathan.dray)
Component: Power-VideoAssignee: acpi_power-video
Status: CLOSED CODE_FIX    
Severity: normal CC: lenb, Robert.Moore, rui.zhang
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 2.6.35.2 Subsystem:
Regression: No Bisected commit-id:
Attachments: Acpi dump output

Description Jonathan Dray 2010-08-15 20:59:24 UTC 
This message is displayed 2 times in the dmesg output :

[    1.039683] ACPI: Using IOAPIC for interrupt routing
[    1.040313] [Firmware Bug]: ACPI: ACPI brightness control misses _BQC function
...
[    5.214540] dcdbas dcdbas: Dell Systems Management Base Driver (version 5.6.0-3.2)
[    5.221713] [Firmware Bug]: ACPI: ACPI brightness control misses _BQC function


I have dell Studio XPS 1645 and a Debian sid OS.
I can control the brightness level with the key shortcuts so I suspect it concerns the brightness sensor which is not enabled.
Comment 1 Zhang Rui 2010-08-16 05:38:41 UTC 
No, this is harmless.
It just suggests that there is a firmware bug in the BIOS, which we already have a workaround.
I assume everything works fine, right?
please attach the acpidump of this laptop.
Comment 2 Jonathan Dray 2010-08-16 09:01:57 UTC 
Created attachment 27464 [details]
Acpi dump output
Comment 3 Robert Moore 2010-08-16 15:59:01 UTC 
[Firmware Bug]: ACPI: ACPI brightness control misses _BQC function

This is a rather poor error message. First, "ACPI" is duplicated, and second, it is not clear what the rest of the message really means. It probably should be more like "could not find required _BQC function" or "required _BQC function was not found" or "required _BQC function is missing"
Comment 4 Zhang Rui 2010-08-17 02:40:44 UTC 
patch with updated error message has been sent out.
https://patchwork.kernel.org/patch/119841/
Comment 5 Len Brown 2010-09-29 01:39:17 UTC 
commit e9f74c489c9d4209946c04f29e7a724cb5537206
Author: Zhang Rui <rui.zhang@intel.com>
Date:   Fri Sep 3 10:08:50 2010 +0800

    ACPI video: fix a poor warning message

staged for upstream
Comment 6 Len Brown 2010-10-02 02:17:54 UTC 
shipped in linux-2.6.36-rc6-git2

closed