Il 01/07/2011 21:34, Michel Alexandre Salim ha scritto:
Dear all,
Hello Michel,
I'm not neither experienced nor the maintainer but I'll give my two cents.
I have a Sony Vaio VPCY2 with a backlight control problem -- both with
acpi_backlight=video and acpi_backlight=vendor.
With the former, setting the backlight (with Fn-F5/6) gave the
appearance, as far as
/sys/class/backlight/acpi_video0/{actual_,}brightness is concerned, that
the change took place, however, the screen brightness remained
unchanged.
Here there is something I don't understand, since the _BCM method stores
the brightness level into an EC register (apparently which one depends
whether the notebook is on battery or not, if BNCM is enabled), but no
GFX related methods are then called. The fact that _BQC returns an
updated value proves that it works, but looking at your DSDT I'd say
that no change is indeed applied. Are you experiencing the same issue
under Windows?
Kernel bug report here: https://bugzilla.kernel.org/show_bug.cgi?id=38342
Fedora bug report: https://bugzilla.redhat.com/show_bug.cgi?id=689962
Is the Vaio Y's backlight supposed to be controlled by sony-laptop
instead of by video.ko?
Not necessarily.
Right now with sony-laptop, actual_brightness
always reads -1 no matter what value is written to brightness.
In your laptop SBRT/GBRT methods use zero based values, so -1 is a
reasonable value. But why are you always getting -1 (especially if the
LCD brightness is maximized)? Maybe the if statement "If (^^EC0.BNEN)"
is false, but why?
If there's any information not currently attached to those bug reports
that is needed, please let me know.
Using the sony-laptop provided backlight device, try to dump the EC
registers before and after changing the brightness value. You can use
"ectool" or sysfs (depending on your kernel configuration).
Regards
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