drm/amd/display: Multi-display underflow observed

[Why]
FP2 programming not happening when topology changes occur with multiple
displays.

[How]
Ensure FP2 is programmed whenever global sync changes occur but wait for
VACTIVE first to avoid underflow.
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Acked-by: Bindu Ramamurthy <bindu.r@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2625,26 +2625,6 @@ static void commit_planes_for_stream(struct dc *dc,
 		}
 	}
 
-	if (update_type != UPDATE_TYPE_FAST) {
-		// If changing VTG FP2: wait until back in vactive to program FP2
-		// Need to ensure that pipe unlock happens soon after to minimize race condition
-		for (i = 0; i < dc->res_pool->pipe_count; i++) {
-			struct pipe_ctx *pipe_ctx = &context->res_ctx.pipe_ctx[i];
-
-			if (pipe_ctx->top_pipe || pipe_ctx->stream != stream)
-				continue;
-
-			if (!pipe_ctx->update_flags.bits.global_sync)
-				continue;
-
-			pipe_ctx->stream_res.tg->funcs->wait_for_state(pipe_ctx->stream_res.tg, CRTC_STATE_VBLANK);
-			pipe_ctx->stream_res.tg->funcs->wait_for_state(pipe_ctx->stream_res.tg, CRTC_STATE_VACTIVE);
-
-			pipe_ctx->stream_res.tg->funcs->set_vtg_params(
-					pipe_ctx->stream_res.tg, &pipe_ctx->stream->timing, true);
-		}
-	}
-
 	if ((update_type != UPDATE_TYPE_FAST) && dc->hwss.interdependent_update_lock)
 		dc->hwss.interdependent_update_lock(dc, context, false);
 	else

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

@@ -1586,7 +1586,10 @@ static void dcn20_program_pipe(
 			&& !pipe_ctx->top_pipe && !pipe_ctx->prev_odm_pipe)
 		hws->funcs.blank_pixel_data(dc, pipe_ctx, !pipe_ctx->plane_state->visible);
 
-	if (pipe_ctx->update_flags.bits.global_sync) {
+	/* Only update TG on top pipe */
+	if (pipe_ctx->update_flags.bits.global_sync && !pipe_ctx->top_pipe
+			&& !pipe_ctx->prev_odm_pipe) {
+
 		pipe_ctx->stream_res.tg->funcs->program_global_sync(
 				pipe_ctx->stream_res.tg,
 				pipe_ctx->pipe_dlg_param.vready_offset,
@@ -1594,8 +1597,11 @@ static void dcn20_program_pipe(
 				pipe_ctx->pipe_dlg_param.vupdate_offset,
 				pipe_ctx->pipe_dlg_param.vupdate_width);
 
+		pipe_ctx->stream_res.tg->funcs->wait_for_state(pipe_ctx->stream_res.tg, CRTC_STATE_VBLANK);
+		pipe_ctx->stream_res.tg->funcs->wait_for_state(pipe_ctx->stream_res.tg, CRTC_STATE_VACTIVE);
+
 		pipe_ctx->stream_res.tg->funcs->set_vtg_params(
-				pipe_ctx->stream_res.tg, &pipe_ctx->stream->timing, false);
+				pipe_ctx->stream_res.tg, &pipe_ctx->stream->timing, true);
 
 		if (hws->funcs.setup_vupdate_interrupt)
 			hws->funcs.setup_vupdate_interrupt(dc, pipe_ctx);
@@ -2570,4 +2576,4 @@ void dcn20_set_disp_pattern_generator(const struct dc *dc,
 {
 	pipe_ctx->stream_res.opp->funcs->opp_set_disp_pattern_generator(pipe_ctx->stream_res.opp, test_pattern,
 			color_space, color_depth, solid_color, width, height, offset);
-}
+}
\ No newline at end of file