drm/amd/display: Restrict multi-disp support for in-game FAMS

[HOW&WHY]
In multi-monitor cases the VBLANK stretch that is required to align both
monitors may be so large that it may create issues for gaming performance.

Use debug value to restrict in-game FAMS support for multi-disp use case.
Reviewed-by: Harry Vanzylldejong <harry.vanzylldejong@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Iswara Nagulendran <iswara.nagulendran@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

@@ -499,6 +499,12 @@ enum dcc_option {
 	DCC_HALF_REQ_DISALBE = 2,
 };
 
+enum in_game_fams_config {
+	INGAME_FAMS_SINGLE_DISP_ENABLE, // enable in-game fams
+	INGAME_FAMS_DISABLE, // disable in-game fams
+	INGAME_FAMS_MULTI_DISP_ENABLE, //enable in-game fams for multi-display
+};
+
 /**
  * enum pipe_split_policy - Pipe split strategy supported by DCN
  *
@@ -951,7 +957,7 @@ struct dc_debug_options {
 	/* Enable dmub aux for legacy ddc */
 	bool enable_dmub_aux_for_legacy_ddc;
 	bool disable_fams;
-	bool disable_fams_gaming;
+	enum in_game_fams_config disable_fams_gaming;
 	/* FEC/PSR1 sequence enable delay in 100us */
 	uint8_t fec_enable_delay_in100us;
 	bool enable_driver_sequence_debug;

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource_helpers.c

@@ -580,7 +580,9 @@ struct dc_stream_state *dcn32_can_support_mclk_switch_using_fw_based_vblank_stre
 	if (!fpo_candidate_stream->allow_freesync)
 		return NULL;
 
-	if (fpo_candidate_stream->vrr_active_variable && dc->debug.disable_fams_gaming)
+	if (fpo_candidate_stream->vrr_active_variable &&
+	((dc->debug.disable_fams_gaming == INGAME_FAMS_DISABLE) ||
+	(context->stream_count > 1 && !(dc->debug.disable_fams_gaming == INGAME_FAMS_MULTI_DISP_ENABLE))))
 		return NULL;
 
 	return fpo_candidate_stream;

drivers/gpu/drm/amd/display/dc/resource/dcn30/dcn30_resource.c

@@ -1996,7 +1996,7 @@ bool dcn30_can_support_mclk_switch_using_fw_based_vblank_stretch(struct dc *dc,
 	if (!context->streams[0]->allow_freesync)
 		return false;
 
-	if (context->streams[0]->vrr_active_variable && dc->debug.disable_fams_gaming)
+	if (context->streams[0]->vrr_active_variable && (dc->debug.disable_fams_gaming == INGAME_FAMS_DISABLE))
 		return false;
 
 	context->streams[0]->fpo_in_use = true;