mirror of
https://github.com/torvalds/linux.git
synced 2025-12-07 20:06:24 +00:00
fab82f4724
ICL/TGL VRR hardware won't allow us to program flipline==vmin. If we do
that the actual effect will be the same as if we had programmed
flipline=vmin+1, which would make the minimum vtotal one scanline taller
than expected.
To compensate for this we reduce vmin by one, and then program
flipline=vmin+1. So we end up with a flipline value that matches
the expected minimum vtotal. Currently this adjustment happens
in intel_vrr_compute_config() which means that crtc_state->vrr.vmin
will no longer be directly usable for the remainder of the high
level VRR code. That is annoying at best, fragile at worst.
Hide the adjustment in low level code instead. This will allow most
of the higher level VRR code to remain blissfully ignorant about this
fact. Afterwards crtc_state->vrr.{vmin,flipline} will be equal
and match the minimum vtotal, exactly how things already work
on ADL+.
The only slight downside is that the actual register value will no
longer match crtc_state->vrr.vmin on ICL/TGL, but that may already
be the case on TGL because the register value will also have been
adjusted by the SCL.
Note that we must change the guardband calculation to account
for intel_vrr_extra_vblank_delay() explicitly. Previously that
was accidentally handled by the earlier vmin reduction by
intel_vrr_flipline_offset().
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250918232226.25295-2-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@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 reStructuredText 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.