Bug 43280

Created attachment 73358 [details]
dmesg from key backlight controls

Forgot bug reported on launchpad about this: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1001767

please attach the dmesg output after boot.
please attach the acpidump output.

Zhang: N2600 is Cedartrail so Imagination SGX545 graphics not Intel graphics. I know there are some things left to sort here on the graphics side too so it may be that not ACPI. I've added myself to the Cc.

Is the Ubuntu kernel built with the GMA500 driver or with the legacy gma500 stub driver ? If you are not sure the dmesg should answer this too

@Alan: I don't think is a Ubuntu bug only. Tested on Fedora too and the backlight controls didn't work either. Look at comment #6 in Launchpad bug:

"
On Fedora 17 beta Live session. 3d acceleration works, performance is not that great, but i can use Gnome-shell from live. The brightness issue is still the same as described, the same message in dmesg about the keycodes and the same non-existent /sys/class/backlight/* entries. Can't use the system settings brightness control either. So the problem is still the same but the 3d acceleration works for the Intel GMA.

Just to complete the answer:
$ uname -r
3.3.0-1.fc17.i686
"

Created attachment 73376 [details]
dmesg after kernel 3.4 boot

Created attachment 73377 [details]
acpidump of HP Mini 110-4100

The GMA has no hardware acceleration support even in FC17 - thats the new software llvmpipe engine in use.

The Ubuntu case doesn't appear to be loading either the stub driver or the gma500 driver so ACPI video wouldn't have been initialised on the 3.4 kernel. Doesn't explain the keycode mystery. Not yet grabbed FC17 to see what it has enabled.

Alan

Some news in 3.5-rc6 kernel. Now keys are recognized but doesn't affect the brightness. Maybe a Xorg issue by now. Here are the details:

$ uname -r
3.5.0-030500rc6-generic
Running Ubuntu 12.04

Driver gma500_gfx loaded on boot.
Entries under /sys/class/backlight previously non-existent.
$ ls /sys/class/backlight/*
/sys/class/backlight/acpi_video0:
actual_brightness  brightness  max_brightness  subsystem  uevent
bl_power           device      power           type

/sys/class/backlight/psb-bl:
actual_brightness  brightness      power      type
bl_power           max_brightness  subsystem  uevent

Brightness is not changing but indicator both in OSE and System Configuration appear (before they didn't). I'll attach the dmesg

Created attachment 75181 [details]
Dmesg of 3.5-rc6 kernel after complete boot

Correction: gma500_gfx is not loaded at boot. Had to load it manually with modprobe. After that and restarting X brightness control didn't work.

I can duplicate that on one of the netbooks I have here. Still investigating further.

Alan,

any update on this?

Tested on Fedora 18-Beta (kernel 3.6.6). The keys for backlight control now work with kernel argument "acpi_backlight=vendor".

The monitor hotplug is not working, should I report a new bug on that one? If so, which information should I get?

I am not sure that my problem related with this bug but last kernel with working Fn+F5/F6 keys on Asus X101CH with Intel GMA 3600 was kernel-3.5.6, running with Fedora 17 and KDE.

With kernnel-3.5.6 and "acpi_backlight=vendor" kernel parameter acpi_listen output when Fn+F5/F6 keys pressed

video/brightnessdown BRTDN 00000087 00000000
 PNP0C14:00 000000d2 00000000
video/brightnessup BRTUP 00000086 00000000
 PNP0C14:00 000000d2 00000000

But with any 3.6.x or 3.7.0 kernels with and without "acpi_backlight=vendor" parameter acpi_listen don't show BRTDN/BRTUP

 PNP0C14:00 000000d2 00000000
 PNP0C14:00 000000d2 00000000

so impossible to change brightness with Fn+F5/F6 keys but brightness can be changed from KDE "Battery Monitor" widget.

Any news about this? With kernel 3.7.3 on debian it still does not work.

(In reply to comment #13)
> Tested on Fedora 18-Beta (kernel 3.6.6). The keys for backlight control now
> work with kernel argument "acpi_backlight=vendor".

This means acpi video driver can't handle backlight, and the gma driver can work.

And the _BCM control method is pretty simple, it just did a memory write in the EC memory space to change brightness level, so it is perhaps a EC firmware bug.

> 
> The monitor hotplug is not working, should I report a new bug on that one? If
> so, which information should I get?

Yes please. Information like which kernels have the problem and which don't, dmesg, acpidump.out would be helpful, thanks.

(In reply to comment #14)
> I am not sure that my problem related with this bug but last kernel with
> working Fn+F5/F6 keys on Asus X101CH with Intel GMA 3600 was kernel-3.5.6,
> running with Fedora 17 and KDE.
> 
> With kernnel-3.5.6 and "acpi_backlight=vendor" kernel parameter acpi_listen
> output when Fn+F5/F6 keys pressed
> 
> video/brightnessdown BRTDN 00000087 00000000
>  PNP0C14:00 000000d2 00000000
> video/brightnessup BRTUP 00000086 00000000
>  PNP0C14:00 000000d2 00000000
> 
> But with any 3.6.x or 3.7.0 kernels with and without "acpi_backlight=vendor"
> parameter acpi_listen don't show BRTDN/BRTUP
> 
>  PNP0C14:00 000000d2 00000000
>  PNP0C14:00 000000d2 00000000
> 
> so impossible to change brightness with Fn+F5/F6 keys but brightness can be
> changed from KDE "Battery Monitor" widget.

Please file a new bug for your problem, this is not the same, thanks.
And please attach acpidump when filing the bug:
# acpidump > acpidump.out

It would be great if you can give the offending commit with a git bisect :-)
Assume the bug code lies in drivers/platform/x86, you can try the following 2 commits to start with:
possibly bad:  eceeb4371240aff22e9a535a2bc57d2311820942
possibly good: 17621e11fda095459e2f986c019f52686c7a4ffb
Thanks.

Fixed somewhere by Intel graphics driver in v3.6 for Joaquín, acpi video driver still does not work, need acpi_backlight=vendor to work.