drm/amd/display: Consolidate HPO enable/disable and restrict only to state transitions.

[WHY]
Previously, we'd disabled HPO whenever an HPO display was disconnected. This
caused other HPO displays to blank whenever one was unplugged.

[HOW]
This change restricts HPO enable/disable to dce110_apply_ctx_to_hw and adds a
helper function (dce110_is_hpo_enabled) that returns true if any HPO displays
are present in a context. We compare the current and previous dc ctx to check
whether HPO is transitioning from on to off or vice versa, and adjust the HPO
state accordingly.
Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Reviewed-by: Chris Park <chris.park@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Natanel Roizenman <natanel.roizenman@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/hwss/dce110/dce110_hwseq.c

@@ -1192,16 +1192,6 @@ void dce110_disable_stream(struct pipe_ctx *pipe_ctx)
 		dccg->funcs->disable_symclk_se(dccg, stream_enc->stream_enc_inst,
 					       link_enc->transmitter - TRANSMITTER_UNIPHY_A);
 	}
-
-	if (dc->link_srv->dp_is_128b_132b_signal(pipe_ctx)) {
-		/* TODO: This looks like a bug to me as we are disabling HPO IO when
-		 * we are just disabling a single HPO stream. Shouldn't we disable HPO
-		 * HW control only when HPOs for all streams are disabled?
-		 */
-		if (pipe_ctx->stream->ctx->dc->hwseq->funcs.setup_hpo_hw_control)
-			pipe_ctx->stream->ctx->dc->hwseq->funcs.setup_hpo_hw_control(
-					pipe_ctx->stream->ctx->dc->hwseq, false);
-	}
 }
 
 void dce110_unblank_stream(struct pipe_ctx *pipe_ctx,
@@ -2288,6 +2278,19 @@ static void dce110_setup_audio_dto(
 	}
 }
 
+static bool dce110_is_hpo_enabled(struct dc_state *context)
+{
+	int i;
+
+	for (i = 0; i < MAX_HPO_DP2_ENCODERS; i++) {
+		if (context->res_ctx.is_hpo_dp_stream_enc_acquired[i]) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
 enum dc_status dce110_apply_ctx_to_hw(
 		struct dc *dc,
 		struct dc_state *context)
@@ -2296,6 +2299,8 @@ enum dc_status dce110_apply_ctx_to_hw(
 	struct dc_bios *dcb = dc->ctx->dc_bios;
 	enum dc_status status;
 	int i;
+	bool was_hpo_enabled = dce110_is_hpo_enabled(dc->current_state);
+	bool is_hpo_enabled = dce110_is_hpo_enabled(context);
 
 	/* reset syncd pipes from disabled pipes */
 	if (dc->config.use_pipe_ctx_sync_logic)
@@ -2338,6 +2343,10 @@ enum dc_status dce110_apply_ctx_to_hw(
 
 	dce110_setup_audio_dto(dc, context);
 
+	if (dc->hwseq->funcs.setup_hpo_hw_control && was_hpo_enabled != is_hpo_enabled) {
+		dc->hwseq->funcs.setup_hpo_hw_control(dc->hwseq, is_hpo_enabled);
+	}
+
 	for (i = 0; i < dc->res_pool->pipe_count; i++) {
 		struct pipe_ctx *pipe_ctx_old =
 					&dc->current_state->res_ctx.pipe_ctx[i];

drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c

@@ -2892,11 +2892,6 @@ void dcn20_enable_stream(struct pipe_ctx *pipe_ctx)
 	struct link_encoder *link_enc = link_enc_cfg_get_link_enc(pipe_ctx->stream->link);
 	struct stream_encoder *stream_enc = pipe_ctx->stream_res.stream_enc;
 
-	if (dc->link_srv->dp_is_128b_132b_signal(pipe_ctx)) {
-		if (dc->hwseq->funcs.setup_hpo_hw_control)
-			dc->hwseq->funcs.setup_hpo_hw_control(dc->hwseq, true);
-	}
-
 	if (dc->link_srv->dp_is_128b_132b_signal(pipe_ctx)) {
 		dto_params.otg_inst = tg->inst;
 		dto_params.pixclk_khz = pipe_ctx->stream->timing.pix_clk_100hz / 10;