drm/amd/display: Add debug options for increasing phantom lines

[Description]
- Add debug option for increasing number of phantom lines
Reviewed-by: Nevenko Stupar <Nevenko.Stupar@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Brian Chang <Brian.Chang@amd.com>
Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dc.h

@@ -852,6 +852,7 @@ struct dc_debug_options {
 	unsigned int force_subvp_num_ways;
 	unsigned int force_mall_ss_num_ways;
 	bool alloc_extra_way_for_cursor;
+	uint32_t subvp_extra_lines;
 	bool force_usr_allow;
 	/* uses value at boot and disables switch */
 	bool disable_dtb_ref_clk_switch;

drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c

@@ -585,6 +585,9 @@ void dcn32_set_phantom_stream_timing(struct dc *dc,
 	num_dpp = vba->NoOfDPP[vba->VoltageLevel][vba->maxMpcComb][vba->pipe_plane[pipe_idx]];
 	phantom_vactive += num_dpp > 1 ? vba->meta_row_height[vba->pipe_plane[pipe_idx]] : 0;
 
+	/* dc->debug.subvp_extra_lines 0 by default*/
+	phantom_vactive += dc->debug.subvp_extra_lines;
+
 	// For backporch of phantom pipe, use vstartup of the main pipe
 	phantom_bp = get_vstartup(&context->bw_ctx.dml, pipes, pipe_cnt, pipe_idx);