drm/amd/display: Test MST port mode support

[WHAT]
Add KUnit tests for dm_dp_mst_is_port_support_mode() covering a mode
that fits uncompressed, a port without a DSC AUX channel, a link with
no common DSC config, the DSC passthrough accept and reject paths, the
last link bandwidth check with a fresh read, a cached value and the
Synaptics quirk, the upstream virtual channel limit and the branch
throughput limit.

[HOW]
Build an MST connector with a stream and a DSC capable encoder, using a
fake dsc_funcs that reports encoder capabilities so the DC bandwidth
range helpers produce usable values. Each path is then selected by
varying the timing, the port DSC capabilities, the full and available
PBN of the topology and the branch descriptor.

Assisted-by: Copilot:Claude-Opus-5
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

0 files changed, 0 insertions, 0 deletions