drm/amd/display: disable FBC on underlay pipe

FBC is not applicable for the underlay pipe,
hence disallow enabling and disabling of the same.

This also fixes the BUG hit of calling sleep in
atomic context.
Signed-off-by: Shirish S <shirish.s@amd.com>
Reviewed-by: Roman Li <Roman.Li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c

@@ -2747,6 +2747,9 @@ static void dce110_program_front_end_for_pipe(
 	struct dc_plane_state *plane_state = pipe_ctx->plane_state;
 	struct xfm_grph_csc_adjustment adjust;
 	struct out_csc_color_matrix tbl_entry;
+#if defined(CONFIG_DRM_AMD_DC_FBC)
+	unsigned int underlay_idx = dc->res_pool->underlay_pipe_index;
+#endif
 	unsigned int i;
 	DC_LOGGER_INIT();
 	memset(&tbl_entry, 0, sizeof(tbl_entry));
@@ -2788,7 +2791,9 @@ static void dce110_program_front_end_for_pipe(
 	program_scaler(dc, pipe_ctx);
 
 #if defined(CONFIG_DRM_AMD_DC_FBC)
-	if (dc->fbc_compressor && old_pipe->stream) {
+	/* fbc not applicable on Underlay pipe */
+	if (dc->fbc_compressor && old_pipe->stream &&
+	    pipe_ctx->pipe_idx != underlay_idx) {
 		if (plane_state->tiling_info.gfx8.array_mode == DC_ARRAY_LINEAR_GENERAL)
 			dc->fbc_compressor->funcs->disable_fbc(dc->fbc_compressor);
 		else