Re: no brightness with acpi video since 3.3 [was Re: Issues with the sony-platform module]

[Karol Babioch <karol@babioch.de>]

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Hi,

Am 16.06.2012 00:37, schrieb Mattia Dongili:
> ok, let's forget about gnome popups for a moment, can you try using the
> sysfs files directly?
I suppose you expect me to use the "acpi_backlight=vendor" parameter?
Because when leaving it out, I don't have any sony subdirectory within
/sys/class/backlight. The only directory is
/sys/class/backlight/acpi_video0, but changing the brightness directly
there doesn't change anything.

With the "acpi_backlight=vendor" boot paramater I got a sony sub
directory (as well as a "nv" subdirectory), but see yourself:

[johnpatcher@vpcs ~]$ ls -l /sys/class/backlight/
insgesamt 0
lrwxrwxrwx 1 root root 0 16. Jun 2012  nv_backlight ->
../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0/card0-LVDS-1/nv_backlight
lrwxrwxrwx 1 root root 0 16. Jun 01:00 sony ->
../../devices/virtual/backlight/sony

I tried to change the brightness via sysfs with the following command:

[root@vpcs sony]# cat actual_brightness brightness max_brightness
-13
-13
242
[root@vpcs sony]# echo 150 > brightness

But nothing changed. dmesg reports the following:

[  419.046851] sony_laptop: found handle 0x0137 (offset: 0x0b)
[  419.169874] sony_laptop: __call_snc_method: [SN07:0x000000000000020b]
[  419.169877] sony_laptop: called SN07 with 0x020b (result: 0x0000)
[  423.710466] sony_laptop: found handle 0x0137 (offset: 0x0b)
[  423.834322] sony_laptop: __call_snc_method: [SN07:0x000000000000020b]
[  423.834324] sony_laptop: called SN07 with 0x020b (result: 0x0000)
[  456.260994] sony_laptop: found handle 0x0137 (offset: 0x0b)
[  456.384772] sony_laptop: __call_snc_method: [SN07:0x000000000000020b]
[  456.384774] sony_laptop: called SN07 with 0x020b (result: 0x0000)
[  461.256523] sony_laptop: found handle 0x0137 (offset: 0x0b)
[  461.386744] sony_laptop: __call_snc_method: [SN07:0x0000000000a3010b]
[  461.386746] sony_laptop: called SN07 with 0xa3010b (result: 0x0000)

Interestingly enough I can change the brightness via
/sys/class/backlight/nv_backlight:

[root@vpcs nv_backlight]# cat actual_brightness brightness max_brightness
100
100
100
[root@vpcs nv_backlight]# echo 50 > brightness

By doing so, dmesg doesn't report anything, although the brightness is
actually changing.

To be honest, I don't understand what is going on here. Why are there
two backlight classes? Why does one work (but isn't registered to
Gnome), while the other doesn't work? I suppose that there is still
something wrong with the acpi video driver, as I have to append
"acpi_backlight=vendor"?

Thanks so far. Hopefully you can make some sense out of this?

Best regards,
Karol Babioch


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