7a2ec4a0a5
To get sensible vblank timestamping behaviour we need to feed
the vmax based timings to the vblank code, otherwise it'll chop
off the scanline counter when it exceeds the minumum vtotal.
Additionally with VRR we have three cases to consider when we
generate the vblank timestamp:
1) we are in vertical active
-> nothing special needs to be done, just return the current
scanout position and the core will calculate the timestamp
corresponding to the past time when the current vertical
active started
2) we are in vertical blank and no push has been sent
-> the hardware will keep extending the vblank presumably
to its maximum length, so we make the timestmap match the
expected time when the max length vblank will end. Since
the timings used for this are now based on vmax nothing
special actually needs to be done
3) we are in vblank and a push has been sent so the vblank is
about to terminate
-> presumably we want the timestmap to accurately reflect
when the vblank will terminate, so we use the sampled
frame timestamp vs. current timestamp to guesstimate
how far along the vblank exit we are, and then we
adjust the reported scanout position accordingly so
that the core will see that the vblank is close to
ending.
v2:
* Fix the else if (use_scanline_Counter) (Manasi)
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210122232647.22688-17-manasi.d.navare@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.