drm/amd/display: Should support p-state under dcn21

drm/amd/display: Should support p-state under dcn21

[Why]
Under DCN21, observe flip_done timeout issue while
running 3D benchmark under MPO case. Timeout is caused
by driver fails validate_bandwidth() during
atomic_commit_tail but passes atomic_check.

Under further analysis, indicates the delta of
atomic_check and atomic_commit_tail are
dc->current_state->bw_ctx.dml.soc.sr_exit_time_us and
dc->current_state->bw_ctx.dml.soc.sr_enter_plus_exit_time_us.

We set validate_mode as DC_VALIDATE_MODE_ONLY while calling
dc_validate_global_state() at atomic_check, but set mode as
DC_VALIDATE_MODE_AND_PROGRAMMING during atomic_commit_tail.
If dc_validate_mode set as DC_VALIDATE_MODE_ONLY,
validate_bandwidth() will skip the wm and dlg calculation.

During commit_tail, validate_bandwidth() is called with
dc_validate_mode set as DC_VALIDATE_MODE_AND_PROGRAMMING and
dc_state->bw_ctx.dml.soc.sr_exit_time_us might get modified
after the wm_calculation and stored into dc->current_state.
Which means dc->current_state->bw_ctx.dml.soc.sr_exit_time_us
might not aligned with the one stored in dm_state->context.
That causes duplicated dm_state->context not aligned with
dc->current_state, and might have bandwidth validation pass
in atomic_check and fail in commit_tail later.

[How]
When the issue occurs, it fails dml_get_voltage_level() with
the condition dm_allow_self_refresh_and_mclk_switch but pass
with the condition dm_allow_self_refresh. However, we should
support p-state. So we should not pass validate_bandwidth by
allowing self refresh only. Change the policy under DCN21.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Signed-off-by: Chuanyu Tseng <chuanyu.tseng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>