drm/dp_mst: Add kunit tests for drm_dp_get_vc_payload_bw()

Add kunit test cases for drm_dp_get_vc_payload_bw() with all the DP1.4
and UHBR link configurations.

v2:
- List test cases in decreasing rate,lane count order matching the
corresponding DP Standard tables. (Ville)
- Add references to the DP Standard tables.
v3:
- Sort the testcases properly.
v4:
- Avoid 'stack frame size x exceeds limit y in
drm_test_dp_mst_calc_pbn_div()' compiler warn. (LKP)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: kernel test robot <lkp@intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v3)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231120125256.2433782-1-imre.deak@intel.com

drm/dp_mst: Fix fractional DSC bpp handling

The current code does '(bpp << 4) / 16' in the MST PBN
calculation, but that is just the same as 'bpp' so the
DSC codepath achieves absolutely nothing. Fix it up so that
the fractional part of the bpp value is actually used instead
of truncated away. 64*1006 has enough zero lsbs that we can
just shift that down in the dividend and thus still manage
to stick to a 32bit divisor.

And while touching this, let's just make the whole thing more
straightforward by making the passed in bpp value .4 binary
fixed point always, instead of having to pass in different
things based on whether DSC is enabled or not.

v2:
- Fix DSC kunit test cases.

Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: David Francis <David.Francis@amd.com>
Cc: Mikita Lipski <mikita.lipski@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Fixes: dc48529fb14e ("drm/dp_mst: Add PBN calculation for DSC modes")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[Imre: Fix kunit test cases]
Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231030155843.2251023-3-imre.deak@intel.com

drm/tests: Split drm_test_dp_mst_sideband_msg_req_decode into parameterized tests

The drm_test_dp_mst_sideband_msg_req_decode repeats the same test
structure with different parameters. This could be better represented
by parameterized tests, provided by KUnit.

In addition to the parameterization of the tests, the test case for the
client ID was changed: instead of using get_random_bytes to generate
the client ID, the client ID is now hardcoded in the test case. This
doesn't affect the assertively of the tests, as this test case only compare
the data going in with the data going out and it doesn't transform the data
itself in any way.

So, convert drm_test_dp_mst_sideband_msg_req_decode into parameterized
tests and make the tests' allocations and prints completely managed by KUnit.

Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20221001223422.857505-2-mcanal@igalia.com

drm/tests: Split drm_test_dp_mst_calc_pbn_mode into parameterized tests

The drm_test_dp_mst_calc_pbn_mode is based on a loop that executes tests
for a couple of test cases. This could be better represented by
parameterized tests, provided by KUnit.

So, convert the drm_test_dp_mst_calc_pbn_mode into parameterized tests.

Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20221001223422.857505-1-mcanal@igalia.com

drm/tests: Change "igt_" prefix to "drm_test_"

With the introduction of KUnit, IGT is no longer the only option to run
the DRM unit tests, as the tests can be run through kunit-tool or on
real hardware with CONFIG_KUNIT.

Therefore, remove the "igt_" prefix from the tests and replace it with
the "drm_test_" prefix, making the tests' names independent from the tool
used.

Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Acked-by: David Gow <davidgow@google.com>
Acked-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220911191756.203118-2-mairacanal@riseup.net

drm: selftest: convert drm_dp_mst_helper selftest to KUnit

Considering the current adoption of the KUnit framework, convert the
DRM DP MST helper selftest to the KUnit API.

Co-developed-by: Rubens Gomes Neto <rubens.gomes.neto@usp.br>
Signed-off-by: Rubens Gomes Neto <rubens.gomes.neto@usp.br>
Tested-by: David Gow <davidgow@google.com>
Acked-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Maíra Canal <maira.canal@usp.br>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220708203052.236290-7-maira.canal@usp.br