[opensuse] "Samsung_Laptop" module not working on Samsung X360 machine‏‏‏


as many recent Samsung Laptop models my box (X360
subnotebook featuring C2D SU9300 and Intel X4500 graphics) does not
support setting the brightness of the backlight via ACPI; rather it
requires a Samsung-specific "SABI" driver.  Supposedly this is provided
for the X360 by SAMSUNG_LAPTOP as of kernel 2.6.39.  The driver should
make the function keys of the machine work under Linux (especially the
brightness and WLAN keys).  Some Fn-keys work prior to 2.6.39, such as
the volume and sleep keys.

Unfortunately, using an opensuse
11.4/kde fresh install and upgrading to via
tumbleweed, I get very erroneous behaviour once the above module is
loaded, as follows:

- pressing the "brightness-up" key does nothing
pressing the "brightness-down" key once switches the display to maximum
brightness, after which no other brightness changes occur when pressing
the "down"-key
- every time one presses the "brightness-down" key, 
the display flickers briefly, and X takes about 40% CPU for a minute or
so, and then reverts to its usual <10% value
- unloading the module will immediately reduce X's CPU load to normal

the brightness keys with the module loaded does not bring up KDE's
brightness applet; pressing the keys without the module does bring up
the applet, which then shows the brightness going up and down but the
actual brightness of the screen remains unaffected.

When the
module is loaded, the system log shows that a X360 laptop is correctly
discovered.  Other than this, nothing is in the log, and nothing is
echoed to the console or the system log when modprobing the module.  The
files in sysfs appear to be correctly created; however, there is also a
"acpi-backlight" class in addition to the "samsung" class that is
managed by the module/driver.  In either case, writing directly into the
sysfs files has no effect whatsoever.  For completeness sake:  the WLAN
key also does not work regardless of loading or unloading the module.

I did quite some googling about the issue but to no avail.  Am I the only one having this problem?

for the long mail, but I hope I provided a complete and useful
description of the issue; will happily provide more info but if things
get complicated I will need step-by-step instructions.

Thanks, BR,

the module did actually work (at least concerning brightness changes)
when I first tried 2.6.39 a while ago, but sorry I don't recall the
version and the circumstances.  However, this seems to indicate that my
current problem may be a regression.

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