Bug 15528 - LCD Brightness Acer Aspire 5740
Summary: LCD Brightness Acer Aspire 5740
Status: CLOSED DUPLICATE of bug 19342
Alias: None
Product: ACPI
Classification: Unclassified
Component: Power-Video (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: Alexey Starikovskiy
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2010-03-12 18:07 UTC by Kyle
Modified: 2010-11-30 04:18 UTC (History)
9 users (show)

See Also:
Kernel Version: 2.6.34-rc1
Subsystem:
Regression: No
Bisected commit-id:


Attachments
acpidump (239.98 KB, text/plain)
2010-03-12 18:08 UTC, Kyle
Details
lslpci (20.85 KB, text/plain)
2010-03-12 18:10 UTC, Kyle
Details
/proc/interupts (1.69 KB, text/plain)
2010-03-12 18:10 UTC, Kyle
Details
xrandr properties (2.20 KB, text/plain)
2010-03-12 18:11 UTC, Kyle
Details
dsdt (48.02 KB, application/octet-stream)
2010-03-12 18:12 UTC, Kyle
Details
ls -l /sys/class/backlight/acpi_video0 (592 bytes, text/plain)
2010-03-15 17:00 UTC, Kyle
Details
patch: evaluate EC _REG explicitly (1.58 KB, patch)
2010-03-25 06:00 UTC, Zhang Rui
Details | Diff
dmesg (30.19 KB, text/plain)
2010-03-25 06:47 UTC, Kyle
Details
grep -i acpi /var/log/messages (398.45 KB, text/plain)
2010-03-25 06:50 UTC, Kyle
Details
dmesg after applying patch from comment 19 (56.04 KB, text/plain)
2010-03-25 22:36 UTC, Sachin Garg
Details
new acpidump with the bios (266.44 KB, text/plain)
2010-04-27 23:28 UTC, Kyle
Details
diff acpidump_new acpidump_old (390.41 KB, text/plain)
2010-04-27 23:32 UTC, Kyle
Details
dmidecode (7.75 KB, text/plain)
2010-05-08 21:57 UTC, Kyle
Details
Add Acer Aspire 5740 to osi_linux dmi list (835 bytes, patch)
2010-05-08 22:32 UTC, Alexey Starikovskiy
Details | Diff
dmesg with acpi_osi=Linux (42.42 KB, text/plain)
2010-05-08 23:22 UTC, Sachin Garg
Details
Add Acer Aspire 5740 to osi_linux dmi list (832 bytes, patch)
2010-05-09 00:43 UTC, Alexey Starikovskiy
Details | Diff

Description Kyle 2010-03-12 18:07:07 UTC
Cannot change LCD Brightness of Acer Aspire 5740-6491

Attaching logs of:
lspci -vv
acpidump
cat /proc/interrupts
xrandr attempts to change brightness
/proc/acpi/dsdt

noumena / # cat /sys/class/backlight/acpi_video0/brightness 
0
noumena / # cat /sys/class/backlight/acpi_video0/actual_brightness 
0
noumena / # cat /sys/class/backlight/acpi_video0/max_brightness    
9
Comment 1 Kyle 2010-03-12 18:08:58 UTC
Created attachment 25487 [details]
acpidump
Comment 2 Kyle 2010-03-12 18:10:09 UTC
Created attachment 25488 [details]
lslpci
Comment 3 Kyle 2010-03-12 18:10:44 UTC
Created attachment 25489 [details]
/proc/interupts
Comment 4 Kyle 2010-03-12 18:11:35 UTC
Created attachment 25490 [details]
xrandr properties
Comment 5 Kyle 2010-03-12 18:12:05 UTC
Created attachment 25491 [details]
dsdt
Comment 6 Zhang Rui 2010-03-15 06:08:45 UTC
please attach the output of "ls -l /sys/class/backlight/acpi_video0/"
Comment 7 Kyle 2010-03-15 17:00:06 UTC
Created attachment 25521 [details]
ls -l /sys/class/backlight/acpi_video0
Comment 8 Zhang Rui 2010-03-16 01:07:41 UTC
> lrwxrwxrwx 1 root root    0 Mar 15 09:58 [0m[01;36mdevice[0m -> 
> [01;34m../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:01/device:06[0m

it seems that this file is corrupted.

please attach the output of "cat //sys/class/backlight/acpi_video0/device/path"
Comment 9 Kyle 2010-03-16 01:18:33 UTC
(In reply to comment #8)
> > lrwxrwxrwx 1 root root    0 Mar 15 09:58 [0m[01;36mdevice[0m -> 
> >
> [01;34m../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:01/device:06[0m
> 
> it seems that this file is corrupted.
> 
> please attach the output of "cat
> //sys/class/backlight/acpi_video0/device/path"

Sorry, it seems that the strange characters are escape characters that are to color the output.  Attached is the output of path:

\_SB_.PCI0.GFX0.DD02
Comment 10 Kyle 2010-03-16 01:20:03 UTC
noumena acpi_video0 # ls -l /sys/class/backlight/acpi_video0/
total 0
-r--r--r-- 1 root root 4096 Mar 15 18:12 actual_brightness
-rw-r--r-- 1 root root 4096 Mar 15 18:13 bl_power
-rw-r--r-- 1 root root 4096 Mar 15 18:12 brightness
lrwxrwxrwx 1 root root    0 Mar 15 18:12 device -> ../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:01/device:06
-r--r--r-- 1 root root 4096 Mar 15 18:12 max_brightness
drwxr-xr-x 2 root root    0 Mar 15 18:13 power
lrwxrwxrwx 1 root root    0 Mar 15 18:12 subsystem -> ../../../../class/backlight
-rw-r--r-- 1 root root 4096 Mar 15 18:12 uevent
Comment 11 Zhang Rui 2010-03-16 01:44:30 UTC
        Method (_BCM, 1, NotSerialized)
        {
            // calculate the value that should be set to EC
            ...
            If (^^^LPCB.EC0.BNCM)
            {
                If (^^^LPCB.EC0.ACST)
                {
                    Store (Local1, ^^^LPCB.EC0.BNAC)
                }
                Else
                {
                    Store (Local1, ^^^LPCB.EC0.BNDC)
                }
            }
            Else
            {
                Store (Local1, ^^^LPCB.EC0.BNAC)
            }
        }

Now it seems that everything goes well.
1. ACPI video driver invoke the _BCM properly.
2. Linux/ACPI runs the AML code correctly.
but the backlight fails to change.


As the backlight control is done via EC,
Alexey, could this be an EC firmware problem?
Comment 12 Zhang Rui 2010-03-16 03:20:01 UTC
*** Bug 15513 has been marked as a duplicate of this bug. ***
Comment 13 Kyle 2010-03-17 14:59:45 UTC
(In reply to comment #11)

> Now it seems that everything goes well.
> 1. ACPI video driver invoke the _BCM properly.
> 2. Linux/ACPI runs the AML code correctly.
> but the backlight fails to change.
> 
> 
> As the backlight control is done via EC,
> Alexey, could this be an EC firmware problem?


If this a problem with the BIOS, or the firmware, where should a bug be filed to have the issue resolved?
Comment 14 Zhang Rui 2010-03-18 01:14:26 UTC
If this is a firmware bug, the problem also exists in Windows, and this usually means that there will be a BIOS upgrade available later.
Comment 15 Sachin Garg 2010-03-18 01:34:14 UTC
But controlling brightness works fine on windows at least on my laptop. Even works up till grub screen
Comment 16 Zhang Rui 2010-03-18 02:06:08 UTC
then what if you boot with boot option "acpi_backlight=vendor" and load the acer-wmi driver?
Comment 17 Sachin Garg 2010-03-18 02:51:43 UTC
(In reply to comment #16)
> then what if you boot with boot option "acpi_backlight=vendor" and load the
> acer-wmi driver?

option acpi_backlight=vendor does not work. I have following message in the dmesg


So I mailed Carlos Corbacho regarding the acer-wmi and following was his response

> 2) I see the following message in my dmesg at the time of booting
>
> acer-wmi: Acer Laptop ACPI-WMI Extras
> acer-wmi: Unable to detect available WMID devices

This looks like a bug in acer-wmi - AFAICT, it should be able to cope with
your laptop. Something with the supported device auto-detection is failing
(the DSDT looks a bit weird compared to the ones I'm used to, but AFAICT,
everything should be supported).

How recent a kernel are you running - does /sys/class/wmi exist, and what's
the contents of that directory if it does?
Comment 18 Zhang Rui 2010-03-18 03:01:42 UTC
re-assign to carlos
Comment 19 Zhang Rui 2010-03-25 06:00:19 UTC
Created attachment 25700 [details]
patch: evaluate EC _REG explicitly

could you please try this patch?
Comment 20 Kyle 2010-03-25 06:46:48 UTC
(In reply to comment #19)
> Created an attachment (id=25700) [details]
> patch: evaluate EC _REG explicitly
> 
> could you please try this patch?

OK.  Tried the patch.  Doesn't seem to solve the problem.  I have noticed that my use of the function keys for brightness now change the settings in xrandr --prop and xbacklight, but the backlight brightness does not change visibly.

Is there any output that would be useful?  attached is dmesg and /var/log/messages

If anything else is useful, let me know.
Comment 21 Kyle 2010-03-25 06:47:16 UTC
Created attachment 25702 [details]
dmesg
Comment 22 Kyle 2010-03-25 06:50:47 UTC
Created attachment 25703 [details]
grep -i acpi /var/log/messages

the whole syslog file is too large to attach here.  this is all references to acpi
Comment 23 Kyle 2010-03-25 18:12:02 UTC
(In reply to comment #19)
> Created an attachment (id=25700) [details]
> patch: evaluate EC _REG explicitly
> 
> could you please try this patch?

I did a grep of the logfile looking for AAAAA and BBBBB explicitly, because the kernel log output doesn't include ACPI (my mistake for the first log attachment here.)  There is an instance of BBBB, here are the lines that immediately surround it:

  70725 Mar 24 23:41:49 noumena kernel: ACPI: bus type pci registered
  70726 Mar 24 23:41:49 noumena kernel: dca service started, version 1.12.1
  70727 Mar 24 23:41:49 noumena kernel: PCI: MMCONFIG for domain 0000 [bus 00-ff] at [mem 0xe0000000-0xefffffff] (base 0xe0000000)
  70728 Mar 24 23:41:49 noumena kernel: PCI: MMCONFIG at [mem 0xe0000000-0xefffffff] reserved in E820
  70729 Mar 24 23:41:49 noumena kernel: PCI: Using configuration type 1 for base access
  70730 Mar 24 23:41:49 noumena kernel: bio: create slab <bio-0> at 0
  70731 Mar 24 23:41:49 noumena kernel: ACPI: EC: Look up EC in DSDT
  70732 Mar 24 23:41:49 noumena kernel: ACPI: BIOS _OSI(Linux) query ignored
  70733 Mar 24 23:41:49 noumena kernel: BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
  70734 Mar 24 23:41:49 noumena kernel: ACPI: Interpreter enabled
  70735 Mar 24 23:41:49 noumena kernel: ACPI: (supports S0 S3 S4 S5)
  70736 Mar 24 23:41:49 noumena kernel: ACPI: Using IOAPIC for interrupt routing
  70737 Mar 24 23:41:49 noumena kernel: ACPI: EC: GPE = 0x17, I/O: command/status = 0x66, data = 0x62
  70738 Mar 24 23:41:49 noumena kernel: ACPI: No dock devices found.
  70739 Mar 24 23:41:49 noumena kernel: \_SB_.PCI0:_OSC invalid UUID
  70740 Mar 24 23:41:49 noumena kernel: _OSC request data:1 8 1f 
  70741 Mar 24 23:41:49 noumena kernel: ACPI: PCI Root Bridge [PCI0] (0000:00)


If there is more that I can provide, let me know.
Comment 24 Sachin Garg 2010-03-25 22:35:20 UTC
I can confirm the same behaviour as in comment 20
Comment 25 Sachin Garg 2010-03-25 22:36:34 UTC
Created attachment 25718 [details]
dmesg after applying patch from comment 19
Comment 26 Zhang Rui 2010-03-26 02:09:45 UTC
(In reply to comment #20)
> (In reply to comment #19)
> I have noticed that
> my use of the function keys for brightness now change the settings in xrandr
> --prop and xbacklight, but the backlight brightness does not change visibly.
> 
This also happens in the kernel without the patch, right?
Comment 27 Sachin Garg 2010-03-26 03:20:59 UTC
(In reply to comment #26)
> (In reply to comment #20)
> > (In reply to comment #19)
> > I have noticed that
> > my use of the function keys for brightness now change the settings in
> xrandr
> > --prop and xbacklight, but the backlight brightness does not change
> visibly.
> > 
> This also happens in the kernel without the patch, right?

I am sorry for the wrong information in my previous comment 24. I can change the values with function keys with out the patch
Comment 28 Kyle 2010-03-26 17:04:39 UTC
(In reply to comment #26)
> (In reply to comment #20)
> > (In reply to comment #19)
> > I have noticed that
> > my use of the function keys for brightness now change the settings in
> xrandr
> > --prop and xbacklight, but the backlight brightness does not change
> visibly.
> > 
> This also happens in the kernel without the patch, right?

That is correct; I didn't mean to create confusion. My apologies.
Comment 29 Carlos Corbacho 2010-03-27 19:16:33 UTC
Assigning this bug back to Zhang Rui - this is an ACPI video bug, not an acer-wmi bug.

The fact that acer-wmi doesn't load on this hardware is a separate bug - even if it did load, it would hand over control of the backlight to the ACPI video driver, so doesn't have any bearing here.
Comment 30 Zhang Rui 2010-03-29 01:38:28 UTC
Sachin,
If I'm right, I think you're using a gateway laptop, and have another bug report for the backlight issue on your laptop, right?
So you don't need to comment here because backlight issues are always HARDWARE DEPENDENT. The problem on your laptops is quite different and your comments always make me confused. :p

Kyle,
I run out of my ideas about this.
It seems that Linux/ACPI video driver is working normal. It invokes the firmware code to change the backlight, but unfortunately this fails. It doesn't look like a software problem to me.
Is there a windows partition on this laptop?
If yes, it would be great if you can verify if the problem also exists in windows.
Comment 31 Sachin Garg 2010-03-29 01:43:19 UTC
Zhang,

But you have closed other bug(#15528) as duplicate of this bug.

Regards,
Sachin.
Comment 32 Kyle 2010-03-29 03:10:14 UTC
(In reply to comment #30)
> Sachin,
> If I'm right, I think you're using a gateway laptop, and have another bug
> report for the backlight issue on your laptop, right?
> So you don't need to comment here because backlight issues are always
> HARDWARE
> DEPENDENT. The problem on your laptops is quite different and your comments
> always make me confused. :p
> 
> Kyle,
> I run out of my ideas about this.
> It seems that Linux/ACPI video driver is working normal. It invokes the
> firmware code to change the backlight, but unfortunately this fails. It
> doesn't
> look like a software problem to me.
> Is there a windows partition on this laptop?
> If yes, it would be great if you can verify if the problem also exists in
> windows.

Unfortunately, there is no windows partition on this machine.  I will not be able to test in Windows.  Perhaps it requires a bios upgrade?  I'm not sure.  If you have any ideas of stuff that I could try, let me know.
Comment 33 Kyle 2010-03-29 03:46:03 UTC
(In reply to comment #32)
> (In reply to comment #30)
> > Sachin,
> > If I'm right, I think you're using a gateway laptop, and have another bug
> > report for the backlight issue on your laptop, right?
> > So you don't need to comment here because backlight issues are always
> HARDWARE
> > DEPENDENT. The problem on your laptops is quite different and your comments
> > always make me confused. :p
> > 
> > Kyle,
> > I run out of my ideas about this.
> > It seems that Linux/ACPI video driver is working normal. It invokes the
> > firmware code to change the backlight, but unfortunately this fails. It
> doesn't
> > look like a software problem to me.
> > Is there a windows partition on this laptop?
> > If yes, it would be great if you can verify if the problem also exists in
> > windows.
> 
> Unfortunately, there is no windows partition on this machine.  I will not be
> able to test in Windows.  Perhaps it requires a bios upgrade?  I'm not sure. 
> If you have any ideas of stuff that I could try, let me know.

Is it of use to note that I can change the brightness of the screen when I am on the grub screen and when I am on the BIOS screen?  When the drm loads and it changes the resolution the brightness maxes out and i can no longer change it.
Comment 34 Zhang Rui 2010-03-29 06:48:01 UTC
(In reply to comment #31)
> Zhang,
> 
> But you have closed other bug(#15528) as duplicate of this bug.
> 
oops, sorry, I thought the problem on your laptop (bug #15513) is a duplicate of bug #15204.

So you can change the backlight via hotkey but you can not change the backlight via the sysfs I/F, right?
did you load the ACPI wmi driver when poking hotkeys?
If yes, will you please verify if it still works without that driver?
Comment 35 Zhang Rui 2010-03-29 06:49:39 UTC
(In reply to comment #33)
> When the drm loads and it
> changes the resolution the brightness maxes out and i can no longer change
> it.

so what if you boot with boot option nomodeset?
can you change the backlight via hotkeys when ACPI wmi driver loaded?
Comment 36 Kyle 2010-03-29 08:43:26 UTC
Loaded with "nomodeset" keeps the brightness at the same level as it was at the grub/BIOS screen, cannot change the level.  An interesting find though: use of function keys changes the value of /sys/class/backlight/acpi_video0/actual_brightness as expected, but the value of /proc/acpi/video/GFX0/DD02/brightness does not update until I have read from actual_brightness?  Perhaps nothing too important there, but an interesting find, nonetheless.

On attempted loading of acer-wmi, dmesg reports: 
acer-wmi: Acer Laptop ACPI-WMI Extras
acer-wmi: Unable to detect available WMID devices
Comment 37 Zhang Rui 2010-03-29 09:02:07 UTC
no, it's wmi driver, not the acer wmi driver.
try "modprobe wmi"
Comment 38 Kyle 2010-03-29 14:52:55 UTC
(In reply to comment #37)
> no, it's wmi driver, not the acer wmi driver.
> try "modprobe wmi"

Sorry for the confusion.  After having loaded the wmi module, the use of the brightness keys shows unhandled ACPI events in my /var/log/messages :

Mar 29 07:44:37 noumena logger: ACPI event unhandled: video DD02 00000087 00000000
Mar 29 07:45:01 noumena logger: ACPI event unhandled: video DD02 00000086 00000000
Mar 29 07:45:02 noumena logger: ACPI event unhandled: video DD02 00000087 00000000

Brightness does not change, stays at whatever setting was selected at the BIOS/GRUB screens.
Comment 39 Sachin Garg 2010-04-08 20:24:50 UTC
(In reply to comment #34)
> (In reply to comment #31)
> > Zhang,
> > 
> > But you have closed other bug(#15528) as duplicate of this bug.
> > 
> oops, sorry, I thought the problem on your laptop (bug #15513) is a duplicate
> of bug #15204.
> 
> So you can change the backlight via hotkey but you can not change the
> backlight
> via the sysfs I/F, right?

No I cannot change the brightness by any means in Linux

> did you load the ACPI wmi driver when poking hotkeys?
> If yes, will you please verify if it still works without that driver?

I get following error.

acer-wmi: Acer Laptop ACPI-WMI Extras
acer-wmi: Unable to detect available WMID devices
Comment 40 Sachin Garg 2010-04-09 04:05:15 UTC
Some success. When I pass acpi=off noacpi in the command line. I am able to control the back-light through the hot keys
Comment 41 Kyle 2010-04-10 17:37:01 UTC
(In reply to comment #40)
> Some success. When I pass acpi=off noacpi in the command line. I am able to
> control the back-light through the hot keys

I can verify that this also works on my laptop.  Unfortunately, you have to give up all other acpi capabilities to enjoy a longer, and unpredictable battery.  haha

Zhang Rui, does this evidence suggest it may yet be an issue with the Linux ACPI?

Sachin, Thanks for the suggestion!!

Best,
Kyle
Comment 42 Sachin Garg 2010-04-25 03:22:29 UTC
Zhang,

Is possible to pass the argument in the video module. So that the brightness does not goes to maximum ? It stays what was selected in the bios or windows.


Since the laptop is too bright at maximum it starts hurting the eyes after an hour

Regards,
Sachin.
Comment 43 Kyle 2010-04-27 23:26:42 UTC
Acer released a BIOS update for the video cards.  I have applied the update. Still no backlight control here.  I am attaching two things: the new acpidump, and the diff of acpidump.new and acpidump already posted.  Perhaps there is something useful in it.

Any other ideas?
Comment 44 Kyle 2010-04-27 23:28:32 UTC
Created attachment 26168 [details]
new acpidump with the bios
Comment 45 Kyle 2010-04-27 23:32:12 UTC
Created attachment 26169 [details]
diff acpidump_new acpidump_old
Comment 46 Kyle 2010-05-08 20:09:20 UTC
Resolved; needed a grub configuration option of acpi_osi="Linux"
Comment 47 Alexey Starikovskiy 2010-05-08 21:38:34 UTC
please attach dmidecode, so we could do osi=Linux automatically...
Comment 48 Kyle 2010-05-08 21:57:00 UTC
Created attachment 26288 [details]
dmidecode

Attaching dmidecode
Comment 49 Alexey Starikovskiy 2010-05-08 22:32:51 UTC
Created attachment 26290 [details]
Add Acer Aspire 5740 to osi_linux dmi list

Please check if this patch works.
Comment 50 Sachin Garg 2010-05-08 23:22:02 UTC
Created attachment 26291 [details]
dmesg with acpi_osi=Linux
Comment 51 Sachin Garg 2010-05-08 23:22:59 UTC
Unfortunately this does not work on my laptop. Still I cannot control brightness. I am attaching the dmesg.
Comment 52 Kyle 2010-05-08 23:23:52 UTC
(In reply to comment #49)
> Created an attachment (id=26290) [details]
> Add Acer Aspire 5740 to osi_linux dmi list
> 
> Please check if this patch works.

after doing a make clean and reinstalling the kernel, loading without the additional argument in grub does not give me the ability to control backlight.

Am I missing some other step?
Comment 53 Jonathan 2010-05-09 00:28:56 UTC
(In reply to comment #50)
> Created an attachment (id=26291) [details]
> dmesg with acpi_osi=Linux

Sachin, you must use quotation marks around the word Linux.
Comment 54 Alexey Starikovskiy 2010-05-09 00:43:25 UTC
Created attachment 26292 [details]
Add Acer Aspire 5740 to osi_linux dmi list

Please try updated patch
Comment 55 Sachin Garg 2010-05-09 01:00:12 UTC
(In reply to comment #53)
> (In reply to comment #50)
> > Created an attachment (id=26291) [details] [details]
> > dmesg with acpi_osi=Linux
> 
> Sachin, you must use quotation marks around the word Linux.

I did use the quotations but it did not help.
Comment 56 Kyle 2010-05-09 05:23:28 UTC
(In reply to comment #54)
> Created an attachment (id=26292) [details]
> Add Acer Aspire 5740 to osi_linux dmi list
> 
> Please try updated patch

This one worked.

Thanks!
Comment 57 Alexey Starikovskiy 2010-05-09 06:47:24 UTC
Great, thanks for testing!
Comment 58 Zhang Rui 2010-05-24 07:23:43 UTC
Hi, Kyle,

(In reply to comment #56)
> (In reply to comment #54)
> > Created an attachment (id=26292) [details] [details]
> > Add Acer Aspire 5740 to osi_linux dmi list
> > 
> > Please try updated patch
> 
> This one worked.

can you change the backlight by poking the /sys/class/backlight/acpi_video0/
or can you change the backlight via hotkeys?
Comment 59 Kyle 2010-05-24 15:05:14 UTC
Zhang, 

I can change using the brightness keys. Attempting to overwrite the values in /sys/class/backlight/acpi_video0/*brightness results in a bash error: Permission Denied. This happens while logged in as root.

Furthermore, changing the value of brightness in /proc/acpi/video/GFX0/DD02/ changes the value within the file, but does not change the brightness of the screen.

The hotkeys work here though.
Comment 60 Joydeep 2010-07-13 06:32:57 UTC
Hello,

I have already updated my BIOS ( acer 5740 ) and also applied the patch at drivers/acpi/blacklist.c and after compiling the kernel, I can control the brightness with hot-keys. But no success with xblacklight command. More over "laptop-mode-tools" is also not able to adjust the brightness. Making any change in "/proc/acpi/video/GFX0/DD02/brightness" file has no effect in practical. Any tricks or kernel level configuration to make it working ? Please let me know.

Thanks
Comment 61 Zhang Rui 2010-07-13 06:43:10 UTC
The backlight control via ACPI video driver on this laptop is broken, so we need to apply the blacklist patch to enable the backlight control via ACPI wmi.

That's why we can change the backlight via hotkeys but we can not via ACPI video backlight I/F.
Comment 62 Joydeep 2010-07-13 06:51:14 UTC
Thanks, Any clue when the driver will be fixed ? Actually without a proper driver , laptop-mode-tools can't control the brightness.

Thanks
Comment 63 Zhang Rui 2010-07-13 07:13:27 UTC
I'm afraid the answer is no.
By reading the code, I even suspect if win7 follows the ACPI video extension or not. Maybe the ACPI method is broken but BIOS writers are not care of it, because windows just do not use it.
We planned to check how windows control the backlight in the near future, but this may take months.
Comment 64 Joydeep 2010-07-13 08:01:33 UTC
Very sad to know this. Can we somehow convince the BIOS programmer to add the required code ? It is difficult to ignore the Linux community now-a-days.
Comment 65 Joydeep 2010-08-07 17:21:23 UTC
Any further progress with the issue ?

thanks
Comment 66 Joydeep 2010-09-09 03:42:29 UTC
Hello,

any news on this issue ? Can we now control the brightness through ACPI ?

Thanks
Comment 67 Zhang Rui 2010-09-29 02:46:12 UTC
with the patch from alexey, the backlight can be changed via hotkey, but does the value of /sys/class/backlight/acpi_video0/actual_brightness also change at the same time?
Comment 68 Kyle 2010-09-29 04:19:20 UTC
(In reply to comment #67)
> with the patch from alexey, the backlight can be changed via hotkey, but does
> the value of /sys/class/backlight/acpi_video0/actual_brightness also change
> at
> the same time?

I can verify that the /sys/class/backlight/acpi_video0/actual_brightness value changes with the brightness changes.
Comment 69 vsn 2010-10-03 21:12:35 UTC
Hi everyone,

I guess I have the same problem with my Acer Travel Mate 5740. This bug was originally committed for a Acer Aspire 5740, but I am experiencing the same problem. Do I have to commit a new bug for Acer Travel Mate 5740?

Problem in two words. Out-of-box brightness adjustment doesn't work. Adding acpi_osi=“Linux” to the kernel parameters fixed the brightness control, so I can adjust the brightness via functional keys. BUT after rebooting all setting are gone and the max brightness is applied, so I have to adjust it manually every time, since the the back light is too bright. Is there a way to fix it? A script or something like this?

Can the manufacture (Acer) help to solve this problem? Acer Support?

Thanks
Comment 70 Jonathan 2010-10-17 20:48:37 UTC
I recently came across a different solution to the LCD brightness issue on the Acer Aspire 5740.  It also applies to other laptops using i915 DRM.

First, compile a kernel (I used 2.6.36-rc8) patched with Matthew Garrett's native backlight control patch:

https://patchwork.kernel.org/patch/163961/ 

Next, add acpi_backlight=vendor to the GRUB kernel line and remove acpi_osi="Linux".

This enables backlight control with more levels of adjustment than the previous method.  It also allows the gnome brightness applet and power manager to control backlight brightness, neither of which worked before.

Kamal Mostafa has additional information here:

https://launchpad.net/~kamalmostafa/+archive/linux-kamal-mjgbacklight
Comment 71 Joydeep 2010-10-19 09:16:42 UTC
Hello,

I have no problem compiling the kernel, but compilation is not successful with the patched kernel. It failed due to the following 

``````````````````
drivers/gpu/drm/i915/intel_lvds.c: In function âintel_lvds_backlight_setupâ:
drivers/gpu/drm/i915/intel_lvds.c:193: error: âstruct backlight_propertiesâ has no member named âtypeâ
drivers/gpu/drm/i915/intel_lvds.c:193: error: âBACKLIGHT_RAWâ undeclared (first use in this function)
drivers/gpu/drm/i915/intel_lvds.c:193: error: (Each undeclared identifier is reported only once
drivers/gpu/drm/i915/intel_lvds.c:193: error: for each function it appears in.)
make[5]: *** [drivers/gpu/drm/i915/intel_lvds.o] Error 1
make[4]: *** [drivers/gpu/drm/i915] Error 2
make[3]: *** [drivers/gpu/drm] Error 2
make[2]: *** [drivers/gpu] Error 2
make[1]: *** [drivers] Error 2
make[1]: Leaving directory `/usr/src/linux-2.6.36-rc8'
make: *** [debian/stamp/build/kernel] Error 2
`````````````````````

What might be the problem ? This is debian squeeze, amd64 arch.

gcc 4:4.4.5-1
make 3.81-8

Thanks
Comment 72 Zhang Rui 2010-10-21 02:59:59 UTC
please apply both of these two patches.
https://patchwork.kernel.org/patch/163961/
https://patchwork.kernel.org/patch/163971/
Comment 73 Joydeep 2010-10-21 04:24:30 UTC
Thanks  Zhang,

Jonathan has already informed me about these 2 patches and I have successfully compiled 2.6.35.7 after patching. Now it is possible to control brightness with

 /sys/class/backlight/intel_backlight/brightness

but the xblacklight as well as the Fn keys are not working. ( tested with acpi_backlight=vendor  too ).  I'll again give a try with the 2.6.36.x series 

- with best regards,
   Joydeep
Comment 74 Joydeep 2010-10-21 16:42:17 UTC
Hello,

Even with the latest 2.6.36.x series, Fn keys are not working after applying the two patches. But when I apply the one more patch from https://bugzilla.kernel.org/attachment.cgi?id=26292  at drivers/acpi/blacklist.c Fn keys are working and without acpi_backlight=vendor

Additionally the /sys/class/backlight/intel_backlight/brightness has an effect too due to the new patches. Though xblacklight has no effect.

Thanks
Comment 75 Jonathan 2010-10-21 17:03:56 UTC
Let's not confuse the issue.  https://bugzilla.kernel.org/attachment.cgi?id=26292 is not related to Matthew Garrett's patches and is not required for his patches to work.
Comment 76 Joe Jackson 2010-10-31 09:14:02 UTC
Using acpi_osi="Linux" in grub fails for me, however if I use acpi_osi= (with no value) it works great, brightness controls work beautifully. Just want to spread the word because I had some serious issues with this, spent a lot of time finding a workaround.
Comment 77 Zhang Rui 2010-11-02 06:52:25 UTC
so can I say that the problem can be workaround by using the i915 brightness control instead of ACPI backlight control?
If yes, I think this is also a duplicate of bug #19342.
Comment 78 Jonathan 2010-11-02 11:03:59 UTC
Zhang,

The answer to your question is yes.  Using the i915 brightness
control instead of ACPI backlight control is a viable workaround.

Jonathan
Comment 79 Zhang Rui 2010-11-03 06:02:38 UTC
As the ACPI backlight control in this bug report is broken, and we can not fix it in Linux/ACPI, the current workaround would be controlling backlight natively.

Bug closed as workaround patch is available.

*** This bug has been marked as a duplicate of bug 19342 ***
Comment 80 Len Brown 2010-11-30 04:18:04 UTC
for the record Re: acpi_osi=Linux

The acpidump in attachment #1 [details] shows that there is no specific
Linux support in the DSDT.  Rather, the way OSI(Linux) is checked
in the DSDT *disables* Windows support by over-writing
the OSYS variable:

    Scope (_SB.PCI0)
    {
        Method (_INI, 0, NotSerialized)
        {
            Store (0x07D0, OSYS)
            If (CondRefOf (_OSI, Local0))
            {
                If (_OSI ("Windows 2001"))
                {
                    Store (0x07D1, OSYS)
                }

                If (_OSI ("Windows 2001 SP1"))
                {
                    Store (0x07D1, OSYS)
                }

                If (_OSI ("Windows 2001 SP2"))
                {
                    Store (0x07D2, OSYS)
                }

                If (_OSI ("Windows 2006"))
                {
                    Store (0x07D6, OSYS)
                }

                If (_OSI ("Windows 2009"))
                {
                    Store (0x07D9, OSYS)
                }

                If (_OSI ("Linux"))
                {
                    Store (0x03E8, OSYS)
                }
            }
        }

There are a number of OS-specific hooks in the DSDT
that depend son OSYS, including on that tells the EC
the OS version via OSTP - very nasty.

Thus the patch in comment #54 that sets acpi_osi=Linux automatically
via DMI makes no logical sense, and can not be applied.

Chances are good that the issues appears due to our
claim of Windows 2009 (win7) compatibility, or possibly
that plus Windows 2006 (vista) compatibility.  Disabling
those w/o disabling claim of compatibility with XP may
be more prudent then using acpi_osi=Linux, or disabling
OSI support entirely with acpi_osi=

eg. acpi_osi="!Windows 2009"
to disable claim of compatibility with Win7

or acpi_osi="!Windows 2009" acpi_osi="!Windows 2006"
to disable claim of compatibility with both Win7 and vista.

The acpidump in comment #44 works the same way.

however, the use of acpi_osi here is a workaround only,
not a permanent fix.

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