f83b94d237
Normally we could be in a deep PkgC state all the way up to the point when DSB starts its execution at the transcoders undelayed vblank. The DSB will then have to wait for the hardware to wake up before it can execute anything. This will waste a huge chunk of the vblank time just waiting, and risks the DSB execution spilling into the vertical active period. That will be very bad, especially when programming the LUTs as the anti-collision logic will cause DSB to corrupt LUT writes during vertical active. To avoid these problems we can instruct the DSB to pre-wake the display engine on a specific scanline so that everything will be 100% ready to go when we hit the transcoder's undelayed vblank. One annoyance is that the scanline is specified as just that, a single scanline. So if we happen to start the DSB execution after passing said scanline no DEwake will happen and we may drop back into some PkgC state before reaching the transcoder's undelayed vblank. To prevent that we'll use the "force DEwake" bit to manually force the display engine to stay awake. We'll then have to clear the force bit again after the DSB is done (the force bit remains effective even when the DSB is otherwise disabled). Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20230606191504.18099-18-ville.syrjala@linux.intel.com Reviewed-by: Uma Shankar <uma.shankar@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.