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