drm/amd/display: Create debugging mechanism for Gaming FAMS

[WHY]
To enable FAMS even during gaming sessions.

[HOW]
By leveraging a new dc.debug parameter.
Reviewed-by: Felipe Clark <felipe.clark@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Gianna Binder <gianna.binder@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

@@ -850,6 +850,7 @@ struct dc_debug_options {
 	/* Enable dmub aux for legacy ddc */
 	bool enable_dmub_aux_for_legacy_ddc;
 	bool disable_fams;
+	bool disable_fams_gaming;
 	/* FEC/PSR1 sequence enable delay in 100us */
 	uint8_t fec_enable_delay_in100us;
 	bool enable_driver_sequence_debug;

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

@@ -1987,11 +1987,10 @@ bool dcn30_can_support_mclk_switch_using_fw_based_vblank_stretch(struct dc *dc,
 	if (!is_refresh_rate_support_mclk_switch_using_fw_based_vblank_stretch(context))
 		return false;
 
-	// check if freesync enabled
 	if (!context->streams[0]->allow_freesync)
 		return false;
 
-	if (context->streams[0]->vrr_active_variable)
+	if (context->streams[0]->vrr_active_variable && dc->debug.disable_fams_gaming)
 		return false;
 
 	context->streams[0]->fpo_in_use = true;

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

@@ -595,11 +595,10 @@ struct dc_stream_state *dcn32_can_support_mclk_switch_using_fw_based_vblank_stre
 	if (!is_refresh_rate_support_mclk_switch_using_fw_based_vblank_stretch(fpo_candidate_stream, fpo_vactive_margin_us))
 		return NULL;
 
-	// check if freesync enabled
 	if (!fpo_candidate_stream->allow_freesync)
 		return NULL;
 
-	if (fpo_candidate_stream->vrr_active_variable)
+	if (fpo_candidate_stream->vrr_active_variable && dc->debug.disable_fams_gaming)
 		return NULL;
 
 	return fpo_candidate_stream;