Bug 15764 - Samsung P460 screen brightness control does not work
Summary: Samsung P460 screen brightness control does not work
Status: REJECTED UNREPRODUCIBLE
Alias: None
Product: ACPI
Classification: Unclassified
Component: Power-Video (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: Zhang Rui
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2010-04-11 15:22 UTC by Claas Langbehn
Modified: 2010-05-10 08:51 UTC (History)
1 user (show)

See Also:
Kernel Version: 2.6.32-19
Subsystem:
Regression: No
Bisected commit-id:


Attachments
dmesg (50.94 KB, text/plain)
2010-04-11 15:22 UTC, Claas Langbehn
Details
dmesg when booting with acpi_osi=Linux (51.15 KB, text/plain)
2010-04-11 15:24 UTC, Claas Langbehn
Details
acpi DSDT (31.34 KB, application/x-ns-proxy-autoconfig)
2010-04-11 15:26 UTC, Claas Langbehn
Details
lspci (2.00 KB, text/plain)
2010-04-11 15:28 UTC, Claas Langbehn
Details
lspci -vn (7.67 KB, text/plain)
2010-04-11 15:35 UTC, Claas Langbehn
Details
lspci -vvv (19.97 KB, text/plain)
2010-04-11 15:36 UTC, Claas Langbehn
Details
dmidecode (9.48 KB, text/plain)
2010-04-11 15:36 UTC, Claas Langbehn
Details
biosdecode (710 bytes, text/plain)
2010-04-11 15:37 UTC, Claas Langbehn
Details

Description Claas Langbehn 2010-04-11 15:22:12 UTC
Created attachment 25948 [details]
dmesg

System: Samsung P460 notebook, BIOS-version 07LQ (current version)
Core 2 Duo P7350 2x 2.00GHz, Intel GMA X4500HD IGP

$ cat /proc/acpi/video/GFX0/DD04/brightness 
levels:  25 35 45 60 70 80 90 100
current: 100

$ echo -n 25 > /proc/acpi/video/GFX0/DD04/brightness 
has no effect on the brightness

It seems to me that this is caused by the system BIOS:

$ dmesg | grep brightness
[    0.208482] [Firmware Bug]: ACPI: ACPI brightness control misses _BQC function

I also tried booting with acpi_osi=Linux but with no changes.
Comment 1 Claas Langbehn 2010-04-11 15:24:54 UTC
Created attachment 25949 [details]
dmesg when booting with acpi_osi=Linux
Comment 2 Claas Langbehn 2010-04-11 15:26:44 UTC
Created attachment 25950 [details]
acpi DSDT
Comment 3 Claas Langbehn 2010-04-11 15:28:21 UTC
Created attachment 25951 [details]
lspci
Comment 4 Claas Langbehn 2010-04-11 15:35:10 UTC
Created attachment 25952 [details]
lspci -vn
Comment 5 Claas Langbehn 2010-04-11 15:36:07 UTC
Created attachment 25953 [details]
lspci -vvv
Comment 6 Claas Langbehn 2010-04-11 15:36:58 UTC
Created attachment 25954 [details]
dmidecode
Comment 7 Claas Langbehn 2010-04-11 15:37:42 UTC
Created attachment 25955 [details]
biosdecode
Comment 8 Claas Langbehn 2010-04-11 15:52:24 UTC
I forgot to mention that the hotkeys for brightness control Fn+cursor_up (increase brightness) and FN+cursor_down (decrease brightness) also don't function. The key scancodes are reported to syslog:

# Brightness up
kernel: [ 2495.235118] atkbd.c: Unknown key pressed (translated set 2, code 0x88 on isa0060/serio0).
kernel: [ 2495.235127] atkbd.c: Use 'setkeycodes e008 <keycode>' to make it known.

# Brightness down
kernel: [ 2496.991297] atkbd.c: Unknown key pressed (translated set 2, code 0x89 on isa0060/serio0).
kernel: [ 2496.991306] atkbd.c: Use 'setkeycodes e009 <keycode>' to make it known.


$ acpi -c
Cooling 0: LCD 0 of 7
Cooling 1: Processor 0 of 10
Cooling 2: Processor 0 of 10
Cooling 3: Fan 0 of 1
Cooling 4: Fan 0 of 1

What's cooling 0 about?


The notebook also has an ambient light sensor. I did not find a way to read the values. Any hints? Under windows this is used to auto-adjust the screen brightness according to the ambient light.
Comment 9 Zhang Rui 2010-04-13 08:49:07 UTC
                        Method (_BCM, 1, NotSerialized)
                        {
                            If (LGreaterEqual (OSYS, 0x07D6))
                            {
                                Store (Arg0, BRTL)
                                SECS (0xA6)
                            }
                        }

        Method (SECS, 1, Serialized)
        {
            Acquire (MSEC, 0xFFFF)
            Store (Arg0, SECI)
            Store (Zero, TRPS)
            Release (MSEC)
        }

As the BIOS changes the backlight in SMM, I don't think there is anything we can do if it doesn't work.

(In reply to comment #8)
> The notebook also has an ambient light sensor. I did not find a way to read
> the
> values. Any hints? Under windows this is used to auto-adjust the screen
> brightness according to the ambient light.

This is a hint.
I have a HP laptop with ambient light sensor. And I can not change the backlight manually in Windows, unless I disable the ambient light sensor.

So can you please disable it and try again? (BTW, there is a hotkey to enable/disable the ALS on my laptop)
Comment 10 Zhang Rui 2010-05-10 06:40:02 UTC
ping...
Comment 11 Claas Langbehn 2010-05-10 08:47:47 UTC
There is a windows utility to activate the ambient light sensor, it was disabled by default. I did not try to enable it because I did not expect it to work with linux.

I wrote an email to the support@samsung, and they replied that they could not help me as they only support Windows. They know about this linux issue, but they don't want to help. Sorry Samsung, but that's not acceptable. I'll buy a Lenovo or HP now.

Since I returned the notebook to the dealer, I can not do further tests.

What shall we do with the status of this bug? Close it as it seems to be a bug of the notbook's BIOS?
Comment 12 Zhang Rui 2010-05-10 08:51:27 UTC
okay, close this bug report as we can not reproduce it for now.
we can re-open it if the bug can be reproduced by anybody else.

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