drm/amd/display: fix dcn315 single stream crb allocation

Change to improve avoiding asymetric crb calculations for single stream
scenarios.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Dmytro Laktyushkin <dmytro.laktyushkin@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@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/dcn315/dcn315_resource.c

@@ -1628,6 +1628,10 @@ static bool allow_pixel_rate_crb(struct dc *dc, struct dc_state *context)
 	int i;
 	struct resource_context *res_ctx = &context->res_ctx;
 
+	/*Don't apply for single stream*/
+	if (context->stream_count < 2)
+		return false;
+
 	for (i = 0; i < dc->res_pool->pipe_count; i++) {
 		if (!res_ctx->pipe_ctx[i].stream)
 			continue;
@@ -1727,19 +1731,23 @@ static int dcn315_populate_dml_pipes_from_context(
 		pipe_cnt++;
 	}
 
-	/* Spread remaining unreserved crb evenly among all pipes, use default policy if not enough det or single pipe */
+	/* Spread remaining unreserved crb evenly among all pipes*/
 	if (pixel_rate_crb) {
 		for (i = 0, pipe_cnt = 0, crb_idx = 0; i < dc->res_pool->pipe_count; i++) {
 			pipe = &res_ctx->pipe_ctx[i];
 			if (!pipe->stream)
 				continue;
 
+			/* Do not use asymetric crb if not enough for pstate support */
+			if (remaining_det_segs < 0) {
+				pipes[pipe_cnt].pipe.src.det_size_override = 0;
+				continue;
+			}
+
 			if (!pipe->top_pipe && !pipe->prev_odm_pipe) {
 				bool split_required = pipe->stream->timing.pix_clk_100hz >= dcn_get_max_non_odm_pix_rate_100hz(&dc->dml.soc)
 						|| (pipe->plane_state && pipe->plane_state->src_rect.width > 5120);
 
-				if (remaining_det_segs < 0 || crb_pipes == 1)
-					pipes[pipe_cnt].pipe.src.det_size_override = 0;
 				if (remaining_det_segs > MIN_RESERVED_DET_SEGS)
 					pipes[pipe_cnt].pipe.src.det_size_override += (remaining_det_segs - MIN_RESERVED_DET_SEGS) / crb_pipes +
 							(crb_idx < (remaining_det_segs - MIN_RESERVED_DET_SEGS) % crb_pipes ? 1 : 0);
@@ -1755,6 +1763,7 @@ static int dcn315_populate_dml_pipes_from_context(
 				}
 				/* Convert segments into size for DML use */
 				pipes[pipe_cnt].pipe.src.det_size_override *= DCN3_15_CRB_SEGMENT_SIZE_KB;
+
 				crb_idx++;
 			}
 			pipe_cnt++;