drm/amd/display: Workaround to increase phantom pipe vactive in pipesplit

[Why]
Certain high resolution displays exhibit DCC line corruption with SubVP
enabled. This is likely due to insufficient DCC meta data buffered
immediately after the mclk switch.

[How]
Add workaround to increase phantom pipe vactive height by
meta_row_height number of lines, thus increasing the amount of meta data
buffered immediately after mclk switch finishes.
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: George Shen <george.shen@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/dml/dcn32/dcn32_fpu.c

@@ -531,9 +531,11 @@ void dcn32_set_phantom_stream_timing(struct dc *dc,
 	unsigned int i, pipe_idx;
 	struct pipe_ctx *pipe;
 	uint32_t phantom_vactive, phantom_bp, pstate_width_fw_delay_lines;
+	unsigned int num_dpp;
 	unsigned int vlevel = context->bw_ctx.dml.vba.VoltageLevel;
 	unsigned int dcfclk = context->bw_ctx.dml.vba.DCFCLKState[vlevel][context->bw_ctx.dml.vba.maxMpcComb];
 	unsigned int socclk = context->bw_ctx.dml.vba.SOCCLKPerState[vlevel];
+	struct vba_vars_st *vba = &context->bw_ctx.dml.vba;
 
 	dc_assert_fp_enabled();
 
@@ -569,6 +571,11 @@ void dcn32_set_phantom_stream_timing(struct dc *dc,
 	phantom_vactive = get_subviewport_lines_needed_in_mall(&context->bw_ctx.dml, pipes, pipe_cnt, pipe_idx) +
 				pstate_width_fw_delay_lines + dc->caps.subvp_swath_height_margin_lines;
 
+	// W/A for DCC corruption with certain high resolution timings.
+	// Determing if pipesplit is used. If so, add meta_row_height to the phantom vactive.
+	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;
+
 	// For backporch of phantom pipe, use vstartup of the main pipe
 	phantom_bp = get_vstartup(&context->bw_ctx.dml, pipes, pipe_cnt, pipe_idx);