https://bugzilla.kernel.org/show_bug.cgi?id=47841
Alessio Gaeta <alga...@gmail.com> changed:
What |Removed |Added
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CC| |alga...@gmail.com
--- Comment #24 from Alessio Gaeta <alga...@gmail.com> 2013-02-14 13:45:39 ---
Hello,
I also own an Asus X53S (slightly different though from the Rthomsen's one, but
the DSDT is basically identical). Here my experience ad issues with the
backlight. I'm on Linux kernel 3.7.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CASE A: boot without specifying acpi_backlight=vendor (thus backlight managed
by video instead of asus-wmi/asus-nb-wmi)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1. `ls /sys/class/backlight` gives:
/sys/class/backlight/acpi_video0
/sys/class/backlight/acpi_video1
/sys/class/backlight/intel_backlight
2. `grep . /sys/class/backlight/*/*` with backlight at maximum (cleaned up
output):
/sys/class/backlight/acpi_video0/actual_brightness:10
/sys/class/backlight/acpi_video0/bl_power:0
/sys/class/backlight/acpi_video0/brightness:10
/sys/class/backlight/acpi_video0/max_brightness:10
/sys/class/backlight/acpi_video0/type:firmware
/sys/class/backlight/acpi_video1/actual_brightness:10
/sys/class/backlight/acpi_video1/bl_power:0
/sys/class/backlight/acpi_video1/brightness:10
/sys/class/backlight/acpi_video1/max_brightness:10
/sys/class/backlight/acpi_video1/type:firmware
/sys/class/backlight/intel_backlight/actual_brightness:4882
/sys/class/backlight/intel_backlight/bl_power:0
/sys/class/backlight/intel_backlight/brightness:4882
/sys/class/backlight/intel_backlight/max_brightness:4882
/sys/class/backlight/intel_backlight/type:raw
3. `grep . /sys/class/backlight/*/*` with backlight reduced by Fn-key gives an
identical output, so files under /sys/class/backlight do not get updated, while
Fn-keys work correctly. The gnome-control-center brightness slider does not get
updated.
4. `echo <new_brightness> > /sys/class/backlight/[acpi_video[0|1] |
intel_backlight]/brightness` actually changes the LCD brightness and updates
(only) the corresponding actual_brightness file (not all three). The
gnome-control-center brightness slider does not get updated.
5. Adjusting brightness through the gnome-control-center brightness slider
works, but only the files /sys/class/backlight/acpi_video1 get updated.
6. `dmesg |grep -i acpi` shows two warnings (among other things):
ACPI Warning: _BQC returned an invalid level (20120913/video-486)
(one for acpi_video device, I guess).
7. Pressing Fn-keys with `acpi_listen` running gives only a sequence of:
PNP0C14:01 000000ff 00000000
(I guess because everything is managed via WMI, so this is only a notification
for the WMI event).
8. Pressing Fn-keys with `udevamd monitor` running gives nothing.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CASE B: boot specifying acpi_backlight=vendor (thus backlight is managed by
asus-wmi/asus-nb-wmi)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1. `ls /sys/class/backlight` gives:
/sys/class/backlight/asus-nb-wmi
/sys/class/backlight/intel_backlight
2. `grep . /sys/class/backlight/*/*` with backlight at maximum (cleaned up
output):
/sys/class/backlight/asus-nb-wmi/actual_brightness:10
/sys/class/backlight/asus-nb-wmi/bl_power:0
/sys/class/backlight/asus-nb-wmi/brightness:10
/sys/class/backlight/asus-nb-wmi/max_brightness:10
/sys/class/backlight/asus-nb-wmi/type:platform
/sys/class/backlight/intel_backlight/actual_brightness:4882
/sys/class/backlight/intel_backlight/bl_power:0
/sys/class/backlight/intel_backlight/brightness:4882
/sys/class/backlight/intel_backlight/max_brightness:4882
/sys/class/backlight/intel_backlight/type:raw
3. `grep . /sys/class/backlight/*/*` with backlight reduced by Fn-key gives:
/sys/class/backlight/asus-nb-wmi/actual_brightness:7
/sys/class/backlight/asus-nb-wmi/bl_power:0
/sys/class/backlight/asus-nb-wmi/brightness:7
/sys/class/backlight/asus-nb-wmi/max_brightness:10
/sys/class/backlight/asus-nb-wmi/type:platform
/sys/class/backlight/intel_backlight/actual_brightness:4882
/sys/class/backlight/intel_backlight/bl_power:0
/sys/class/backlight/intel_backlight/brightness:4882
/sys/class/backlight/intel_backlight/max_brightness:4882
/sys/class/backlight/intel_backlight/type:raw
So asus-wmi actually seems to manage correctly the ACPI brightness stuff. The
gnome-control-center brightness slider does not get updated.
4. `echo <new_brightness> > /sys/class/backlight/[asus-nb-wmi |
intel_backlight]/brightness` actually changes the LCD brightness and updates
(only) the corresponding actual_brightness file (not all three). The
gnome-control-center brightness slider does not get updated.
5. Adjusting brightness through the gnome-control-center brightness slider
works, but only the files under /sys/class/backlight/intel_backlight get
updated.
6. In `dmesg |grep -i acpi` the _BCQ warnings are gone.
7. Pressing Fn-keys with `acpi_listen` running still gives only a sequence of:
PNP0C14:01 000000ff 00000000
8. Pressing Fn-keys with `udevamd monitor` running gives a sequence of:
KERNEL[1084.782718] change
/devices/platform/asus-nb-wmi/backlight/asus-nb-wmi (backlight)
UDEV [1084.783201] change
/devices/platform/asus-nb-wmi/backlight/asus-nb-wmi (backlight)
Which AFAIK is the correct notification behavior (and is a missing feature of
Gnome not intercepting and managing them).
~~~~~~~~~~~
Conclusions
~~~~~~~~~~~
On this machine I think one should go with acpi_backlight=vendor and wait for a
correct backlight uevent support by desktop environments.
Still it is unclear to me which is the interaction path between desktop power
management and the files under /sys/class/backlight (i.e. see points A5 and
B5). I would be glad if anyone can explain that.
And still I could not understand why the generic ACPI drivers are preferred by
default over the specific ones, which are supposed to better handle the
devices. Could anyone explain that too?
Sorry for the lenghty post, but I tried to be exhaustive. Thanks!
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