drm/amd/display: enabling stream after HPD low to high happened

[Why]
1. No real HPD plug in/out but HPD happens,
 the driver notifies OS connection changed.
2. No display in target.

When HPD goes low to high,
the driver should regard as HPD and enter setmode flow.

[How]
In this case, even stream didn't change but still retrain.
Signed-off-by: Chiawen Huang <chiawen.huang@amd.com>
Signed-off-by: Charlene Liu <charlene.liu@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -704,6 +704,7 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
 
 	if (new_connection_type != dc_connection_none) {
 		link->type = new_connection_type;
+		link->link_state_valid = false;
 
 		/* From Disconnected-to-Connected. */
 		switch (link->connector_signal) {
@@ -2631,6 +2632,8 @@ void core_link_enable_stream(
 			stream->phy_pix_clk,
 			pipe_ctx->stream_res.audio != NULL);
 
+	pipe_ctx->stream->link->link_state_valid = true;
+
 	if (dc_is_dvi_signal(pipe_ctx->stream->signal))
 		pipe_ctx->stream_res.stream_enc->funcs->dvi_set_stream_attribute(
 			pipe_ctx->stream_res.stream_enc,

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

@@ -2642,6 +2642,10 @@ bool pipe_need_reprogram(
 	if (is_vsc_info_packet_changed(pipe_ctx_old->stream, pipe_ctx->stream))
 		return true;
 
+	if (false == pipe_ctx_old->stream->link->link_state_valid &&
+		false == pipe_ctx_old->stream->dpms_off)
+		return true;
+
 	return false;
 }
 

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

@@ -75,6 +75,7 @@ struct dc_link {
 	enum dc_irq_source irq_source_hpd_rx;/* aka DP Short Pulse  */
 	bool is_hpd_filter_disabled;
 	bool dp_ss_off;
+	bool link_state_valid;
 
 	/* caps is the same as reported_link_cap. link_traing use
 	 * reported_link_cap. Will clean up.  TODO

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

@@ -2023,8 +2023,10 @@ enum dc_status dce110_apply_ctx_to_hw(
 		if (pipe_ctx->stream == NULL)
 			continue;
 
-		if (pipe_ctx->stream == pipe_ctx_old->stream)
+		if (pipe_ctx->stream == pipe_ctx_old->stream &&
+			pipe_ctx->stream->link->link_state_valid) {
 			continue;
+		}
 
 		if (pipe_ctx_old->stream && !pipe_need_reprogram(pipe_ctx_old, pipe_ctx))
 			continue;