09aef2c48e
Pre-DCE12 needs special treatment for BTR / low framerate compensation for more stable behaviour: According to comments in the code and some testing on DCE-8 and DCE-11, DCE-11 and earlier only apply VTOTAL_MIN/MAX programming with a lag of one frame, so the special BTR hw programming for intermediate fixed duration frames must be done inside the current frame at flip submission in atomic commit tail, ie. one vblank earlier, and the fixed refresh intermediate frame mode must be also terminated one vblank earlier on pre-DCE12 display engines. To achieve proper termination on < DCE-12 shift the point when the switch-back from fixed vblank duration to variable vblank duration happens from the start of VBLANK (vblank irq, as done on DCE-12+) to back-porch or end of VBLANK (handled by vupdate irq handler). We must leave the switch-back code inside VBLANK irq for DCE12+, as before. Doing this, we get much better behaviour of BTR for up-sweeps, ie. going from short to long frame durations (~high to low fps) and for constant framerate flips, as tested on DCE-8 and DCE-11. Behaviour is still not quite as good as on DCN-1 though. On down-sweeps, going from long to short frame durations (low fps to high fps) < DCE-12 is a little bit improved, although by far not as much as for up-sweeps and constant fps. v2: Fix some wrong locking, as pointed out by Nicholas. v3: Simplify if-condition in vupdate-irq - nit by Nicholas. Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com> Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.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.