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use low level P-Unit semaphore lock for axp288 register accesses directly and for more than one access a time, to reduce the number of times this semaphore is locked and released which is an expensive operation. i2c-bus to the XPower is shared between the kernel and the SoCs P-Unit. The P-Unit has a semaphore wich the kernel must lock for axp288 register accesses. When the P-Unit semaphore is locked CPU and GPU power states cannot change or the system will freeze. The P-Unit semaphore lock is already managed inside the regmap access logic, but for each access the semaphore is locked and released. So use directly iosf_mbi_(un)block_punit_i2c_access(), we are safe in doing so because nested calls to the same semaphore are turned to nops. Suggested-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Hans de Goede <hdegoede@redhat.com> Tested-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.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.