backlight regression on ASUS F6S: inverted brightness control

DISCUSSION Kel Modderman 3 participants 9 messages Dec 27, 2008 – Jan 4, 2009 ACPI

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Kel Modderman

author

2008-12-27 20:11 UTC #0 lore raw

Hi,

After booting Linux 2.6.28 the backlight control actions have now reversed,
ie: attempting to make backlight brighter makes it dimmer and vice versa.

The recent backlight changes (video vs. vendor) seem to have the result of allowing the ASUS F6S backlight hardware be driven via the acpi/video driver rather than the vendor/asus_laptop driver as per printk:

asus-laptop: Brightness ignored, must be controlled by ACPI video driver

Linux < 2.6.28
--------------

# cat /sys/class/backlight/asus-laptop/max_brightness
15

# Makes backlight brightest

# echo 15 > /sys/class/backlight/asus-laptop/brightness

# Makes backlight dimmest

# echo 0 > /sys/class/backlight/asus-laptop/brightness

Linux = 2.6.28
--------------

# cat /sys/class/backlight/acpi_video0/max_brightness
13

# Makes backlight brightest

# echo 0 > /sys/class/backlight/acpi_video0/brightness

# Makes backlight dimmest

# echo 13 > /sys/class/backlight/acpi_video0/brightness

A search for "linux 2.6.28 backlight" led to an Ubuntu bug report [1] which describes an ASUS notebook user with the same situation.

[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/305935

Is it possible to have the ACPI video driver to behave correctly on this hardware?

I'd like to provide any further required information. I've attached a bzip tarball containing:
/sys/devices/platform/asus-laptop/infos
/proc/acpi/dsdt
dmesg output
dmidecode output

Thanks, Kel.

Zhang Rui

2008-12-29 01:09 UTC #1 lore raw

hi,

This is a duplicate of bug
http://bugzilla.kernel.org/show_bug.cgi?id=12302
please try the patch at
http://bugzilla.kernel.org/show_bug.cgi?id=12037#c5

thanks,
rui

Quoted 50 lines · Kel Modderman

Hi,
After booting Linux 2.6.28 the backlight control actions have now reversed,
ie: attempting to make backlight brighter makes it dimmer and vice versa.
The recent backlight changes (video vs. vendor) seem to have the result of allowing the ASUS F6S backlight hardware be driven via the acpi/video driver rather than the vendor/asus_laptop driver as per printk:
asus-laptop: Brightness ignored, must be controlled by ACPI video driver
Linux < 2.6.28
--------------
# cat /sys/class/backlight/asus-laptop/max_brightness
15
# Makes backlight brightest
# echo 15 > /sys/class/backlight/asus-laptop/brightness
# Makes backlight dimmest
# echo 0 > /sys/class/backlight/asus-laptop/brightness
Linux = 2.6.28
--------------
# cat /sys/class/backlight/acpi_video0/max_brightness
13
# Makes backlight brightest
# echo 0 > /sys/class/backlight/acpi_video0/brightness
# Makes backlight dimmest
# echo 13 > /sys/class/backlight/acpi_video0/brightness
A search for "linux 2.6.28 backlight" led to an Ubuntu bug report [1] which describes an ASUS notebook user with the same situation.
[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/305935
Is it possible to have the ACPI video driver to behave correctly on this hardware?
I'd like to provide any further required information. I've attached a bzip tarball containing:
/sys/devices/platform/asus-laptop/infos
/proc/acpi/dsdt
dmesg output
dmidecode output
Thanks, Kel.

Kel Modderman

author

2008-12-29 08:39 UTC #2 lore raw

Quoted 6 lines · On Monday 29 December 2008 11:07:32 Zhang Rui wrote:

hi,
This is a duplicate of bug
http://bugzilla.kernel.org/show_bug.cgi?id=12302
please try the patch at
http://bugzilla.kernel.org/show_bug.cgi?id=12037#c5

When patch is applied backlight control returned to normality.

Thanks, Kel.

Zhang Rui

2008-12-30 01:40 UTC #3 lore raw

Quoted 10 lines · Kel Modderman

Quoted 6 lines · On Monday 29 December 2008 11:07:32 Zhang Rui wrote:
hi,
This is a duplicate of bug
http://bugzilla.kernel.org/show_bug.cgi?id=12302
please try the patch at
http://bugzilla.kernel.org/show_bug.cgi?id=12037#c5
When patch is applied backlight control returned to normality.

please attach the output of "grep . /proc/acpi/video/*/*/*" both before and after applying this patch.

thanks,
rui

Kel Modderman

author

2008-12-30 16:02 UTC #4 lore raw

Quoted 9 lines · On Tuesday 30 December 2008 11:37:47 Zhang Rui wrote:

Quoted 8 lines · Kel Modderman
Quoted 6 lines · On Monday 29 December 2008 11:07:32 Zhang Rui wrote:
hi,
This is a duplicate of bug
http://bugzilla.kernel.org/show_bug.cgi?id=12302
please try the patch at
http://bugzilla.kernel.org/show_bug.cgi?id=12037#c5

Quoted 4 lines

Quoted 2 lines
When patch is applied backlight control returned to normality.
please attach the output of "grep . /proc/acpi/video/*/*/*" both before and after applying this patch.

Attached.

Thanks, Kel

/proc/acpi/video/VGA/CRTD/brightness:<not supported> /proc/acpi/video/VGA/CRTD/EDID:<not supported>
/proc/acpi/video/VGA/CRTD/info:device_id: 0x0100
/proc/acpi/video/VGA/CRTD/info:type: UNKNOWN
/proc/acpi/video/VGA/CRTD/info:known by bios: no
/proc/acpi/video/VGA/CRTD/state:state: 0x1d
/proc/acpi/video/VGA/CRTD/state:query: 0x00
/proc/acpi/video/VGA/DVID/brightness:<not supported> /proc/acpi/video/VGA/DVID/EDID:<not supported>
/proc/acpi/video/VGA/DVID/info:device_id: 0x0120
/proc/acpi/video/VGA/DVID/info:type: UNKNOWN
/proc/acpi/video/VGA/DVID/info:known by bios: no
/proc/acpi/video/VGA/DVID/state:state: 0x1d
/proc/acpi/video/VGA/DVID/state:query: 0x00
/proc/acpi/video/VGA/LCDD/brightness:levels: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 /proc/acpi/video/VGA/LCDD/brightness:current: 0 /proc/acpi/video/VGA/LCDD/EDID:<not supported>
/proc/acpi/video/VGA/LCDD/info:device_id: 0x0110
/proc/acpi/video/VGA/LCDD/info:type: UNKNOWN
/proc/acpi/video/VGA/LCDD/info:known by bios: no
/proc/acpi/video/VGA/LCDD/state:state: 0x1f
/proc/acpi/video/VGA/LCDD/state:query: 0x01

/proc/acpi/video/VGA/CRTD/brightness:<not supported> /proc/acpi/video/VGA/CRTD/EDID:<not supported>
/proc/acpi/video/VGA/CRTD/info:device_id: 0x0100
/proc/acpi/video/VGA/CRTD/info:type: UNKNOWN
/proc/acpi/video/VGA/CRTD/info:known by bios: no
/proc/acpi/video/VGA/CRTD/state:state: 0x1d
/proc/acpi/video/VGA/CRTD/state:query: 0x00
/proc/acpi/video/VGA/DVID/brightness:<not supported> /proc/acpi/video/VGA/DVID/EDID:<not supported>
/proc/acpi/video/VGA/DVID/info:device_id: 0x0120
/proc/acpi/video/VGA/DVID/info:type: UNKNOWN
/proc/acpi/video/VGA/DVID/info:known by bios: no
/proc/acpi/video/VGA/DVID/state:state: 0x1d
/proc/acpi/video/VGA/DVID/state:query: 0x00
/proc/acpi/video/VGA/LCDD/brightness:levels: 15 14 0 1 2 3 4 5 6 7 8 9 10 11 12 13 /proc/acpi/video/VGA/LCDD/brightness:current: 13 /proc/acpi/video/VGA/LCDD/EDID:<not supported>
/proc/acpi/video/VGA/LCDD/info:device_id: 0x0110
/proc/acpi/video/VGA/LCDD/info:type: UNKNOWN
/proc/acpi/video/VGA/LCDD/info:known by bios: no
/proc/acpi/video/VGA/LCDD/state:state: 0x1f
/proc/acpi/video/VGA/LCDD/state:query: 0x01

Zhang Rui

2008-12-31 03:36 UTC #5 lore raw

the ACPI video backlight I/F on your laptop is broken.
could you please boot with acpi_backlight=vendor and see if it works at before?

BTW: please attach the output of "grep . /proc/acpi/video/*/*/*" in
1. 2.6.28 kenrel & boot with "acpi_backlight=vendor"
2. an earlier working kernel, say 2.6.26.

thanks,
rui

Quoted 10 lines · Kel Modderman

Quoted 9 lines · On Tuesday 30 December 2008 11:37:47 Zhang Rui wrote:
Quoted 8 lines · Kel Modderman
Quoted 6 lines · On Monday 29 December 2008 11:07:32 Zhang Rui wrote:
hi,
This is a duplicate of bug
http://bugzilla.kernel.org/show_bug.cgi?id=12302
please try the patch at
http://bugzilla.kernel.org/show_bug.cgi?id=12037#c5

Quoted 8 lines

Quoted 4 lines
Quoted 2 lines
When patch is applied backlight control returned to normality.
please attach the output of "grep . /proc/acpi/video/*/*/*" both before and after applying this patch.
Attached.
Thanks, Kel

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Zhang Rui

2008-12-31 06:24 UTC #6 lore raw

Hi, thomas,

we got a couple of regressions caused by the acpi video detect patch set.
IMO, the reason is that they have buggy ACPI video extension implemented. and these laptops used to control the backlight via platform drivers.

you can refer to this thread or the bug:
http://bugzilla.kernel.org/show_bug.cgi?id=12037
http://bugzilla.kernel.org/show_bug.cgi?id=12235
http://bugzilla.kernel.org/show_bug.cgi?id=12249
http://bugzilla.kernel.org/show_bug.cgi?id=12302

I have fixed one by overriding the DSDT.
the source code of the customized DSDT can be found at
http://bugzilla.kernel.org/show_bug.cgi?id=12249#c32

so IMO, acpi_video_backlight_support should be able to verify if BIOS offers buggy ACPI backlight control methods and returns false in this case. but then we need to move a lot of ACPI video code (acpi_video_init_brightness) to video_detect.c, which doesn't sound quite good. what do you think?

thanks,
rui

Quoted 28 lines · Zhang Rui

the ACPI video backlight I/F on your laptop is broken.
could you please boot with acpi_backlight=vendor and see if it works at before?
BTW: please attach the output of "grep . /proc/acpi/video/*/*/*" in
1. 2.6.28 kenrel & boot with "acpi_backlight=vendor"
2. an earlier working kernel, say 2.6.26.
thanks,
rui
Quoted 15 lines · Kel Modderman
Quoted 13 lines · On Tuesday 30 December 2008 11:37:47 Zhang Rui wrote:
Quoted 10 lines · Kel Modderman
Quoted 6 lines · On Monday 29 December 2008 11:07:32 Zhang Rui wrote:
hi,
This is a duplicate of bug
http://bugzilla.kernel.org/show_bug.cgi?id=12302
please try the patch at
http://bugzilla.kernel.org/show_bug.cgi?id=12037#c5
When patch is applied backlight control returned to normality.
please attach the output of "grep . /proc/acpi/video/*/*/*" both before and after applying this patch.

Quoted 8 lines

Quoted 3 lines
Attached.
Thanks, Kel
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Matthew Garrett

2008-12-31 11:50 UTC #7 lore raw

In reply to Zhang Rui

Quoted 1 line · Zhang Rui

the ACPI video backlight I/F on your laptop is broken.

It looks pretty easy for us to be able to fix up the lists in this case. If it's present on several systems then we probably ought to.

Kel Modderman

author

2009-01-04 20:49 UTC #8 lore raw

In reply to Zhang Rui

Quoted 6 lines · On Wednesday 31 December 2008 13:33:28 Zhang Rui wrote:

the ACPI video backlight I/F on your laptop is broken.
could you please boot with acpi_backlight=vendor and see if it works at before?
BTW: please attach the output of "grep . /proc/acpi/video/*/*/*" in
1. 2.6.28 kenrel & boot with "acpi_backlight=vendor"

/proc/acpi/video/VGA/CRTD/brightness:<not supported> /proc/acpi/video/VGA/CRTD/EDID:<not supported>
/proc/acpi/video/VGA/CRTD/info:device_id: 0x0100
/proc/acpi/video/VGA/CRTD/info:type: UNKNOWN
/proc/acpi/video/VGA/CRTD/info:known by bios: no
/proc/acpi/video/VGA/CRTD/state:state: 0x1d
/proc/acpi/video/VGA/CRTD/state:query: 0x00
/proc/acpi/video/VGA/DVID/brightness:<not supported> /proc/acpi/video/VGA/DVID/EDID:<not supported>
/proc/acpi/video/VGA/DVID/info:device_id: 0x0120
/proc/acpi/video/VGA/DVID/info:type: UNKNOWN
/proc/acpi/video/VGA/DVID/info:known by bios: no
/proc/acpi/video/VGA/DVID/state:state: 0x1d
/proc/acpi/video/VGA/DVID/state:query: 0x00
/proc/acpi/video/VGA/LCDD/brightness:<not supported> /proc/acpi/video/VGA/LCDD/EDID:<not supported>
/proc/acpi/video/VGA/LCDD/info:device_id: 0x0110
/proc/acpi/video/VGA/LCDD/info:type: UNKNOWN
/proc/acpi/video/VGA/LCDD/info:known by bios: no
/proc/acpi/video/VGA/LCDD/state:state: 0x1f
/proc/acpi/video/VGA/LCDD/state:query: 0x01

Quoted 1 line

2. an earlier working kernel, say 2.6.26.

/proc/acpi/video/VGA/CRTD/brightness:<not supported> /proc/acpi/video/VGA/CRTD/EDID:<not supported>
/proc/acpi/video/VGA/CRTD/info:device_id: 0x0100
/proc/acpi/video/VGA/CRTD/info:type: UNKNOWN
/proc/acpi/video/VGA/CRTD/info:known by bios: no
/proc/acpi/video/VGA/CRTD/state:state: 0x1d
/proc/acpi/video/VGA/CRTD/state:query: 0x00
/proc/acpi/video/VGA/DVID/brightness:<not supported> /proc/acpi/video/VGA/DVID/EDID:<not supported>
/proc/acpi/video/VGA/DVID/info:device_id: 0x0120
/proc/acpi/video/VGA/DVID/info:type: UNKNOWN
/proc/acpi/video/VGA/DVID/info:known by bios: no
/proc/acpi/video/VGA/DVID/state:state: 0x1d
/proc/acpi/video/VGA/DVID/state:query: 0x00
/proc/acpi/video/VGA/LCDD/brightness:levels: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 /proc/acpi/video/VGA/LCDD/brightness:current: 13 /proc/acpi/video/VGA/LCDD/EDID:<not supported>
/proc/acpi/video/VGA/LCDD/info:device_id: 0x0110
/proc/acpi/video/VGA/LCDD/info:type: UNKNOWN
/proc/acpi/video/VGA/LCDD/info:known by bios: no
/proc/acpi/video/VGA/LCDD/state:state: 0x1f
/proc/acpi/video/VGA/LCDD/state:query: 0x01

Thanks, Kel.
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