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Sony Notebook Control Driver (SNC) Readme
-----------------------------------------
Copyright (C) 2004- 2005 Stelian Pop <stelian@popies.net>
Copyright (C) 2007 Mattia Dongili <malattia@linux.it>
This mini-driver drives the SNC device present in the ACPI BIOS of
the Sony Vaio laptops.
It gives access to some extra laptop functionalities. In its current
form, this driver let the user set or query the screen brightness
through the backlight subsystem and remove/apply power to some devices.
Backlight control:
------------------
If your laptop model supports it, you will find sysfs files in the
/sys/class/backlight/sony/
directory. You will be able to query and set the current screen
brightness:
brightness get/set screen brightness (an iteger
between 0 and 7)
actual_brightness reading from this file will query the HW
to get real brightness value
max_brightness the maximum brightness value
Platform specific:
------------------
Loading the sony-laptop module will create a
/sys/devices/platform/sony-laptop/
directory populated with some files.
You then read/write integer values from/to those files by using
standard UNIX tools.
The files are:
brightness_default screen brightness which will be set
when the laptop will be rebooted
cdpower power on/off the internal CD drive
audiopower power on/off the internal sound card
lanpower power on/off the internal ethernet card
(only in debug mode)
Note that some files may be missing if they are not supported
by your particular laptop model.
Example usage:
# echo "1" > /sys/devices/platform/sony-laptop/brightness_default
sets the lowest screen brightness for the next and later reboots,
# echo "8" > /sys/devices/platform/sony-laptop/brightness_default
sets the highest screen brightness for the next and later reboots,
# cat /sys/devices/platform/sony-laptop/brightness_default
retrieves the value.
# echo "0" > /sys/devices/platform/sony-laptop/audiopower
powers off the sound card,
# echo "1" > /sys/devices/platform/sony-laptop/audiopower
powers on the sound card.
Development:
------------
If you want to help with the development of this driver (and
you are not afraid of any side effects doing strange things with
your ACPI BIOS could have on your laptop), load the driver and
pass the option 'debug=1'.
REPEAT: DON'T DO THIS IF YOU DON'T LIKE RISKY BUSINESS.
In your kernel logs you will find the list of all ACPI methods
the SNC device has on your laptop. You can see the GCDP/GCDP methods
used to pwer on/off the CD drive, but there are others.
I HAVE NO IDEA WHAT THOSE METHODS DO.
The sony-laptop driver creates, for some of those methods (the most
current ones found on several Vaio models), an entry under
/sys/devices/platform/sony-laptop, just like the 'cdpower' one.
You can create other entries corresponding to your own laptop methods by
further editing the source (see the 'sony_acpi_values' table, and add a new
entry to this table with your get/set method names using the
HANDLE_NAMES macro).
Your mission, should you accept it, is to try finding out what
those entries are for, by reading/writing random values from/to those
files and find out what is the impact on your laptop.
Should you find anything interesting, please report it back to me,
I will not disavow all knowledge of your actions :)
Bugs/Limitations:
-----------------
* This driver is not based on official documentation from Sony
(because there is none), so there is no guarantee this driver
will work at all, or do the right thing. Although this hasn't
happened to me, this driver could do very bad things to your
laptop, including permanent damage.
* The sony-laptop and sonypi drivers do not interact at all. In the
future, sonypi could use sony-laptop to do (part of) its business.
* spicctrl, which is the userspace tool used to communicate with the
sonypi driver (through /dev/sonypi) does not try to use the
sony-laptop driver. In the future, spicctrl could try sonypi first,
and if it isn't present, try sony-laptop instead.
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