Commit c9beecc5 authored by Jimmy Kizito's avatar Jimmy Kizito Committed by Alex Deucher
Browse files

drm/amd/display: Add work around for tunneled MST. 



[Why]
Certain USB4 docks do not seem to be able to handle disabling
DSC once it has been enabled on an MST stream. This can result
in blank displays.

[How]
As a work around, always enable DSC on docks exhibiting this issue. The
flag to indicate the use of DSC for MST streams on a USB4 dock is set
during detection of the dock and only cleared when the USB4 dock is
disconnected.

Reviewed-by: default avatarJun Lei <Jun.Lei@amd.com>
Reviewed-by: default avatarAric Cyr <Aric.Cyr@amd.com>
Acked-by: default avatarBhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: default avatarJimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 5ceaebcd

drivers/gpu/drm/amd/display/dc/core/dc_link.c

+16 −0
Original line number Diff line number Diff line
@@ -758,6 +758,18 @@ static bool detect_dp(struct dc_link *link, 
			dal_ddc_service_set_transaction_type(link->ddc,

							     sink_caps->transaction_type);



#if defined(CONFIG_DRM_AMD_DC_DCN)

			/* Apply work around for tunneled MST on certain USB4 docks. Always use DSC if dock

			 * reports DSC support.

			 */

			if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA &&

					link->type == dc_connection_mst_branch &&

					link->dpcd_caps.branch_dev_id == DP_BRANCH_DEVICE_ID_90CC24 &&

					link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_SUPPORT &&

					!link->dc->debug.dpia_debug.bits.disable_mst_dsc_work_around)

				link->wa_flags.dpia_mst_dsc_always_on = true;

#endif



#if defined(CONFIG_DRM_AMD_DC_HDCP)

			/* In case of fallback to SST when topology discovery below fails

			 * HDCP caps will be querried again later by the upper layer (caller
@@ -1203,6 +1215,10 @@ static bool dc_link_detect_helper(struct dc_link *link, 
			LINK_INFO("link=%d, mst branch is now Disconnected\n",

				  link->link_index);



			/* Disable work around which keeps DSC on for tunneled MST on certain USB4 docks. */

			if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA)

				link->wa_flags.dpia_mst_dsc_always_on = false;



			dm_helpers_dp_mst_stop_top_mgr(link->ctx, link);



			link->mst_stream_alloc_table.stream_count = 0;

drivers/gpu/drm/amd/display/dc/core/dc_resource.c

+10 −10
Original line number Diff line number Diff line
@@ -2256,16 +2256,6 @@ enum dc_status dc_validate_global_state( 


	if (!new_ctx)

		return DC_ERROR_UNEXPECTED;

#if defined(CONFIG_DRM_AMD_DC_DCN)



	/*

	 * Update link encoder to stream assignment.

	 * TODO: Split out reason allocation from validation.

	 */

	if (dc->res_pool->funcs->link_encs_assign && fast_validate == false)

		dc->res_pool->funcs->link_encs_assign(

			dc, new_ctx, new_ctx->streams, new_ctx->stream_count);

#endif



	if (dc->res_pool->funcs->validate_global) {

		result = dc->res_pool->funcs->validate_global(dc, new_ctx);
@@ -2317,6 +2307,16 @@ enum dc_status dc_validate_global_state( 
		if (!dc->res_pool->funcs->validate_bandwidth(dc, new_ctx, fast_validate))

			result = DC_FAIL_BANDWIDTH_VALIDATE;



#if defined(CONFIG_DRM_AMD_DC_DCN)

	/*

	 * Only update link encoder to stream assignment after bandwidth validation passed.

	 * TODO: Split out assignment and validation.

	 */

	if (result == DC_OK && dc->res_pool->funcs->link_encs_assign && fast_validate == false)

		dc->res_pool->funcs->link_encs_assign(

			dc, new_ctx, new_ctx->streams, new_ctx->stream_count);

#endif



	return result;

}

drivers/gpu/drm/amd/display/dc/dc.h

+2 −1
Original line number Diff line number Diff line
@@ -508,7 +508,8 @@ union dpia_debug_options { 
		uint32_t disable_dpia:1;

		uint32_t force_non_lttpr:1;

		uint32_t extend_aux_rd_interval:1;

		uint32_t reserved:29;

		uint32_t disable_mst_dsc_work_around:1;

		uint32_t reserved:28;

	} bits;

	uint32_t raw;

};

drivers/gpu/drm/amd/display/dc/dc_link.h

+2 −0
Original line number Diff line number Diff line
@@ -191,6 +191,8 @@ struct dc_link { 
		bool dp_skip_DID2;

		bool dp_skip_reset_segment;

		bool dp_mot_reset_segment;

		/* Some USB4 docks do not handle turning off MST DSC once it has been enabled. */

		bool dpia_mst_dsc_always_on;

	} wa_flags;

	struct link_mst_stream_allocation_table mst_stream_alloc_table;