drm/i915/kunit: DP link: add fallback tests

Add KUnit tests for DP link fallback selection across eDP, SST, and MST.
Verify that the fallback logic properly selects the maximum allowed
configuration, iterates through allowed configurations, and disables
failed configs as expected.

These tests include UHBR vs. non-UHBR conditions, MST vs. SST mode,
and validate that subsequent fallback selections respect the updated
allowed configuration mask.

v2:
- Rebase on changes using a filter object instead of a mask of
  configuration indices.
- Rebase on changes using an iteration object.

Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260701153204.4124150-35-imre.deak@intel.com
This commit is contained in:
Imre Deak 2026-07-01 18:32:03 +03:00
commit 4fee95d4f8