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The amount of plane registers we have to write has been steadily increasing, putting more pressure on the vblank evasion mechanism and forcing us to increase its time budget. Let's try to take some of the pressure off by splitting plane updates into two parts: 1) write all non-self arming plane registers, ie. the registers where the write actually does nothing until a separate arming register is also written which will cause the hardware to latch the new register values at the next start of vblank 2) write all self arming plane registers, ie. registers which always just latch at the next start of vblank, and registers which also arm other registers to do so Here we just provide the mechanism, but don't actually implement the split on any platform yet. so everything stays now in the _arm() hooks. Subsequently we can move a whole bunch of stuff into the _noarm() part, especially in more modern platforms where the number of registers we have to write is also the greatest. On older platforms this is less beneficial probably, but no real reason to deviate from a common behaviour. And let's sprinkle some TODOs around the areas that will need adapting. Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20211018115030.3547-5-ville.syrjala@linux.intel.com Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@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.