drm/i915: Workaround broken BIOS DBUF configuration on TGL/RKL

On TGL/RKL the BIOS likes to use some kind of bogus DBUF layout
that doesn't match what the spec recommends. With a single active
pipe that is not going to be a problem, but with multiple pipes
active skl_commit_modeset_enables() goes into an infinite loop
since it can't figure out any order in which it can commit the
pipes without causing DBUF overlaps between the planes.

We'd need some kind of extra DBUF defrag stage in between to
make the transition possible. But that is clearly way too complex
a solution, so in the name of simplicity let's just sanitize the
DBUF state by simply turning off all planes when we detect a
pipe encroaching on its neighbours' DBUF slices. We only have
to disable the primary planes as all other planes should have
already been disabled (if they somehow were enabled) by
earlier sanitization steps.

And for good measure let's also sanitize in case the DBUF
allocations of the pipes already seem to overlap each other.

Cc: <stable@vger.kernel.org> # v5.14+
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4762
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220204141818.1900-3-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

0 files changed, 0 insertions, 0 deletions