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1Sony Notebook Control Driver (SNC) Readme
2-----------------------------------------
3 Copyright (C) 2004- 2005 Stelian Pop <stelian@popies.net>
4 Copyright (C) 2007 Mattia Dongili <malattia@linux.it>
5
6This mini-driver drives the SNC device present in the ACPI BIOS of
7the Sony Vaio laptops.
8
9It gives access to some extra laptop functionalities. In its current
10form, this driver let the user set or query the screen brightness
11through the backlight subsystem and remove/apply power to some devices.
12
13Backlight control:
14------------------
15If your laptop model supports it, you will find sysfs files in the
16/sys/class/backlight/sony/
17directory. You will be able to query and set the current screen
18brightness:
19 brightness get/set screen brightness (an iteger
20 between 0 and 7)
21 actual_brightness reading from this file will query the HW
22 to get real brightness value
23 max_brightness the maximum brightness value
24
25
26Platform specific:
27------------------
28Loading the sony-laptop module will create a
29/sys/devices/platform/sony-laptop/
30directory populated with some files.
31
32You then read/write integer values from/to those files by using
33standard UNIX tools.
34
35The files are:
36 brightness_default screen brightness which will be set
37 when the laptop will be rebooted
38 cdpower power on/off the internal CD drive
39 audiopower power on/off the internal sound card
40 lanpower power on/off the internal ethernet card
41 (only in debug mode)
42
43Note that some files may be missing if they are not supported
44by your particular laptop model.
45
46Example usage:
47 # echo "1" > /sys/devices/platform/sony-laptop/brightness_default
48sets the lowest screen brightness for the next and later reboots,
49 # echo "8" > /sys/devices/platform/sony-laptop/brightness_default
50sets the highest screen brightness for the next and later reboots,
51 # cat /sys/devices/platform/sony-laptop/brightness_default
52retrieves the value.
53
54 # echo "0" > /sys/devices/platform/sony-laptop/audiopower
55powers off the sound card,
56 # echo "1" > /sys/devices/platform/sony-laptop/audiopower
57powers on the sound card.
58
59Development:
60------------
61
62If you want to help with the development of this driver (and
63you are not afraid of any side effects doing strange things with
64your ACPI BIOS could have on your laptop), load the driver and
65pass the option 'debug=1'.
66
67REPEAT: DON'T DO THIS IF YOU DON'T LIKE RISKY BUSINESS.
68
69In your kernel logs you will find the list of all ACPI methods
70the SNC device has on your laptop. You can see the GCDP/GCDP methods
71used to pwer on/off the CD drive, but there are others.
72
73I HAVE NO IDEA WHAT THOSE METHODS DO.
74
75The sony-laptop driver creates, for some of those methods (the most
76current ones found on several Vaio models), an entry under
77/sys/devices/platform/sony-laptop, just like the 'cdpower' one.
78You can create other entries corresponding to your own laptop methods by
79further editing the source (see the 'sony_acpi_values' table, and add a new
80entry to this table with your get/set method names using the
81HANDLE_NAMES macro).
82
83Your mission, should you accept it, is to try finding out what
84those entries are for, by reading/writing random values from/to those
85files and find out what is the impact on your laptop.
86
87Should you find anything interesting, please report it back to me,
88I will not disavow all knowledge of your actions :)
89
90Bugs/Limitations:
91-----------------
92
93* This driver is not based on official documentation from Sony
94 (because there is none), so there is no guarantee this driver
95 will work at all, or do the right thing. Although this hasn't
96 happened to me, this driver could do very bad things to your
97 laptop, including permanent damage.
98
99* The sony-laptop and sonypi drivers do not interact at all. In the
100 future, sonypi could use sony-laptop to do (part of) its business.
101
102* spicctrl, which is the userspace tool used to communicate with the
103 sonypi driver (through /dev/sonypi) does not try to use the
104 sony-laptop driver. In the future, spicctrl could try sonypi first,
105 and if it isn't present, try sony-laptop instead.
106