3bd554e03e
The "Smart Battery Selector" standard says that when writing SelectorState (0x1), the nibbles which should not be modified need to be masked with 0xff. This is necessary since in contrast to a "Smart Battery Manager", the last three nibbles are writable. Failing to do so might trigger the following cycle: 1. Host accidentally changes power source of the system (3rd nibble) when selecting a battery. 2. Power source is invalid, Selector changes to another power source. 3. Selector notifies host that it changed the power source. 4. Host re-reads some batteries. 5. goto 1 for each re-read battery. This loop might also be entered when a battery which is not present is selected for SMBus access. In the end some workqueues fill up, which causes the system to lockup upon suspend/shutdown. Fix this by correctly masking the value to be written, and avoid selecting batteries which are absent. Tested on a Acer Travelmate 4002WLMi. Signed-off-by: Armin Wolf <W_Armin@gmx.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.