** Changed in: linux-lts-saucy (Ubuntu)
Status: Confirmed => Fix Released
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Title:
[Lenovo T540p, W540] Backlight interfaces not fully work
Lenovo T540p also got fixed by upgrading to the specified BIOS version,
tested on 12.04.4 .
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Title:
[Lenovo T540p, W540] Backlight interfaces not
** Changed in: linux-lts-raring (Ubuntu)
Status: Triaged => Fix Released
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Title:
[Lenovo T540p, W540] Backlight interfaces not fully worki
Brightness auto dim and brightness testing both work now, after BIOS
upgrade, as Chih mentioned in comment #22 .
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Title:
[Lenovo T540p, W540] Bac
A equivalent to INF flag in Linux is to use kernel parameter
acpi_backlight=vendor
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Title:
[Lenovo T540p, W540] Backlight interfaces not fully wo
Confirmed with the test BIOS - GNET62M1.CAP, it fixes this very issue on
W540.
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Title:
[Lenovo T540p, W540] Backlight interfaces not fully workin
Lenovo BIOS engineer commented on Mar. 19 as:
"
//
I understand the situation. Since ThinkPad BIOS assumes that Windows 8
or later OS always uses the OS-driver initiated brightness control
method, so the brightness logic won't work if an OS declares it is Win8
but it uses OS-BIOS initiated brightn
With kernel 3.11.0-17-generic, _BCL returns as below:
[ 4792.647432] Brightness[0] = 100
[ 4792.647439] Brightness[1] = 100
[ 4792.647442] Brightness[2] = 0
[ 4792.647445] Brightness[3] = 1
[ 4792.647447] Brightness[4] = 2
[ 4792.647450] Brightness[5] = 3
[ 4792.647452] Brightness[6] = 4
[ 4792.64
** Changed in: linux-lts-raring (Ubuntu)
Assignee: AceLan Kao (acelankao) => Alex Hung (alexhung)
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Title:
[Lenovo T540p, W540] Backlight int
I am very certain that Linux uses _BCL correctly. I think this bug is
related to _OSI("Windows 2012) which is supported in kernel 3.7 or
later. Some detection may be added to address the issue with Win7.
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OEM BIOS engineer has given the following feedback on Mar. 18:
"
//
It should not be removed, since it is the key process to convert OS brightness
percentage (0-100) to the actual LCD PWM brightness duty value (0-255) along
with the brightness curves which are defined for each LCD panels. If you
Some additional information to #12:
The original code is as below, and it checks BRTW as in #12
Method (_BCM, 1, NotSerialized)
{
Store (Match (\_SB.PCI0.LPC.EC.BRTW, MEQ, Arg0, MTR, 0x00, 0x02),
Local0)
If (LNotEqual (Local0, Ones))
{
BIOS upgrade is impossible in the official way without a battery pack.
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Title:
[Lenovo T540p, W540] Backlight interfaces not fully working
To ma
@Alex, could you please let me know which BIOS version that you are
working on? Is it GNET58WW (2.06)? I'll escalate to Lenovo, thank you!
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Title:
Status changed to 'Confirmed' because the bug affects multiple users.
** Changed in: linux-lts-raring (Ubuntu)
Status: New => Confirmed
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Ti
Status changed to 'Confirmed' because the bug affects multiple users.
** Changed in: linux-lts-saucy (Ubuntu)
Status: New => Confirmed
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Tit
** Attachment added: "acpi.log"
https://bugs.launchpad.net/ubuntu/+source/linux-lts-raring/+bug/1270079/+attachment/4006466/+files/acpi.log
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Ti
>From BIOS AML, the brightness function (ex. _BCM) checks a table before
making actual brightness adjustment. The table is located in DSDT and
attached below:
Name (BRTW, Package (0x12)
{
0x64,
0x64,
0x01,
0x03
There is a new BIOS released on 2/19, but the BIOS CD image seems can't boot
directly from USB disk.
Sorry, I have no time to study it, will let Yung help on this.
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** Changed in: linux-lts-saucy (Ubuntu)
Importance: Undecided => High
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Title:
[Lenovo T540p, W540] Backlight interfaces not fully working
To
** Also affects: linux-lts-saucy (Ubuntu)
Importance: Undecided
Status: New
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Title:
[Lenovo T540p, W540] Backlight interfaces not fully
We later found that the backlight adjustment (using hotkeys) work
normally after enabling the W540's discrete nVidia GPU (through
installing nvidia-prime and nvidia-331 packages.) in Ubuntu 12.04.4.
@Acelan, does this suggest that " to disable the ACPI backlight
interface on these systems" in the
According to comment #4 ,
Tried upgrading W540 BIOS firmware from GNET22WW (1.04 ) to GNET58WW (2.06)
but brightness key still not working.
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Titl
additional note,
there are two testcases will be effected by this issue:
1. The brightness keys
2."Dim screen to save power", that system will dim screen automatically when
it's on battery.
and the second test is a blocker to the certification test, which caused
by backlight interfaces not fully
An updated BIOS (1.12) is available at official Lenovo site:
http://support.lenovo.com/en_US/downloads/detail.page?&DocID=DS039066
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Title:
[Leno
This issue could be fixed by kernel after the below 2 patches are accepted.
I think the second one is still in drm-intel-nightly git tree.
http://lists.freedesktop.org/archives/dri-devel/2013-September/045421.html
http://www.spinics.net/lists/linux-acpi/msg47755.html
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According to Yung's comment on #3, the "Windows 2012" means "Windows 8 and
Server 2012"
The linux kernel will tell the BIOS we are Win8 after kernel 3.7, the kernel
parameter in #3 tells the BIOS that we are Win7.
So, it looks like it's a BIOS issue that has different behavior on Win7 and
Win8.
I've double check this issue with different kernel parameters,
by adding following parameter, the brightness keys and the dim_brightness test
now works fine, even OSD can response correctly.
acpi_osi='!Windows 2012'
but this is still an issue, since changing parameters in
/etc/default/grub will
@AceLan, hi acelan, please help to take a look at this issue
** Changed in: linux-lts-raring (Ubuntu)
Assignee: (unassigned) => AceLan Kao (acelankao)
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** Changed in: linux-lts-raring (Ubuntu)
Importance: Undecided => Medium
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Title:
[Lenovo T540p, W540] Backlight interfaces not fully working
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