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Exercise acquiring and releasing forcewake around register reads. In order to read a register behind a GT powerwell, we need to instruct that powerwell to wake up using a forcewake. When we no longer require the GT powerwell, we tell the GT to release our forcewake. Inside the forcewake, the register read should work but outside it should just return garbage, 0 being the most common garbage. Thus we can detect when we are inside and outside of the forcewake with just a simple register read, and so can verify that the GT powerwell is released when we say so. v2: Picking the right forcewaked register to return 0 outside of forcewake is an art. Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/msgid/20190320080052.27273-1-chris@chris-wilson.co.uk
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.