drm/amd/display: Fix DML failures caused by doubled stereo viewport

[Why]
Side-by-side and Top-and-bottom stereo configurations fail DML mode
validation due to Viewport exceeded.

This is because we consider the planes as being pipe split in pipe
population so we end up doubling the viewport width, eg. from 4k to 8k.

[How]
These pipes technically aren't hsplit, so add a check for determining
whether is_hsplit should be set.
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c

@@ -302,10 +302,17 @@ static void pipe_ctx_to_e2e_pipe_params (
 		struct _vcs_dpi_display_pipe_params_st *input)
 {
 	input->src.is_hsplit = false;
-	if (pipe->top_pipe != NULL && pipe->top_pipe->plane_state == pipe->plane_state)
+
+	/* stereo can never be split */
+	if (pipe->plane_state->stereo_format == PLANE_STEREO_FORMAT_SIDE_BY_SIDE ||
+	    pipe->plane_state->stereo_format == PLANE_STEREO_FORMAT_TOP_AND_BOTTOM) {
+		/* reset the split group if it was already considered split. */
+		input->src.hsplit_grp = pipe->pipe_idx;
+	} else if (pipe->top_pipe != NULL && pipe->top_pipe->plane_state == pipe->plane_state) {
 		input->src.is_hsplit = true;
-	else if (pipe->bottom_pipe != NULL && pipe->bottom_pipe->plane_state == pipe->plane_state)
+	} else if (pipe->bottom_pipe != NULL && pipe->bottom_pipe->plane_state == pipe->plane_state) {
 		input->src.is_hsplit = true;
+	}
 
 	if (pipe->plane_res.dpp->ctx->dc->debug.optimized_watermark) {
 		/*

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c

@@ -2257,6 +2257,14 @@ int dcn20_populate_dml_pipes_from_context(
 			pipes[pipe_cnt].pipe.src.is_hsplit = (res_ctx->pipe_ctx[i].bottom_pipe && res_ctx->pipe_ctx[i].bottom_pipe->plane_state == pln)
 					|| (res_ctx->pipe_ctx[i].top_pipe && res_ctx->pipe_ctx[i].top_pipe->plane_state == pln)
 					|| pipes[pipe_cnt].pipe.dest.odm_combine != dm_odm_combine_mode_disabled;
+
+			/* stereo is never split, nor odm combine */
+			if (pln->stereo_format == PLANE_STEREO_FORMAT_SIDE_BY_SIDE ||
+			    pln->stereo_format == PLANE_STEREO_FORMAT_TOP_AND_BOTTOM) {
+				pipes[pipe_cnt].pipe.src.is_hsplit = false;
+				pipes[pipe_cnt].pipe.src.hsplit_grp = res_ctx->pipe_ctx[i].pipe_idx;
+			}
+
 			pipes[pipe_cnt].pipe.src.source_scan = pln->rotation == ROTATION_ANGLE_90
 					|| pln->rotation == ROTATION_ANGLE_270 ? dm_vert : dm_horz;
 			pipes[pipe_cnt].pipe.src.viewport_y_y = scl->viewport_unadjusted.y;