drm/amd/display: avoid disable otg when dig was disabled

[Why]
This is a workaround for an dcn3.1 hang that happens if otg dispclk
is ramped while otg is on and stream enc is off.
But this w/a should not trigger when we have a dig active.

[How]
Avoid disable otg when dig FE/BE FIFO was not switched.
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Jingwen Zhu <jingwen.zhu@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/clk_mgr/dcn35/dcn35_clk_mgr.c

@@ -120,7 +120,6 @@ static int dcn35_get_active_display_cnt_wa(
 
 	return display_count;
 }
-
 static void dcn35_disable_otg_wa(struct clk_mgr *clk_mgr_base, struct dc_state *context,
 		bool safe_to_lower, bool disable)
 {
@@ -128,14 +127,27 @@ static void dcn35_disable_otg_wa(struct clk_mgr *clk_mgr_base, struct dc_state *
 	int i;
 
 	for (i = 0; i < dc->res_pool->pipe_count; ++i) {
+		struct pipe_ctx *old_pipe = &dc->current_state->res_ctx.pipe_ctx[i];
+		struct pipe_ctx *new_pipe = &context->res_ctx.pipe_ctx[i];
 		struct pipe_ctx *pipe = safe_to_lower
 			? &context->res_ctx.pipe_ctx[i]
 			: &dc->current_state->res_ctx.pipe_ctx[i];
-
+		bool stream_changed_otg_dig_on = false;
 		if (pipe->top_pipe || pipe->prev_odm_pipe)
 			continue;
+		stream_changed_otg_dig_on = old_pipe->stream && new_pipe->stream &&
+		old_pipe->stream != new_pipe->stream &&
+		old_pipe->stream_res.tg == new_pipe->stream_res.tg &&
+		new_pipe->stream->link_enc && !new_pipe->stream->dpms_off &&
+		new_pipe->stream->link->link_enc->funcs->is_dig_enabled &&
+		new_pipe->stream->link->link_enc->funcs->is_dig_enabled(
+		new_pipe->stream->link->link_enc) &&
+		new_pipe->stream_res.stream_enc &&
+		new_pipe->stream_res.stream_enc->funcs->is_fifo_enabled &&
+		new_pipe->stream_res.stream_enc->funcs->is_fifo_enabled(new_pipe->stream_res.stream_enc);
 		if (pipe->stream && (pipe->stream->dpms_off || dc_is_virtual_signal(pipe->stream->signal) ||
-				     !pipe->stream->link_enc)) {
+			!pipe->stream->link_enc) && !stream_changed_otg_dig_on) {
+			/* This w/a should not trigger when we have a dig active */
 			if (disable) {
 				if (pipe->stream_res.tg && pipe->stream_res.tg->funcs->disable_crtc)
 					pipe->stream_res.tg->funcs->disable_crtc(pipe->stream_res.tg);

drivers/gpu/drm/amd/display/dc/dio/dcn35/dcn35_dio_stream_encoder.c

@@ -392,6 +392,14 @@ static void enc35_reset_fifo(struct stream_encoder *enc, bool reset)
 		udelay(10);
 }
 
+static bool enc35_is_fifo_enabled(struct stream_encoder *enc)
+{
+	struct dcn10_stream_encoder *enc1 = DCN10STRENC_FROM_STRENC(enc);
+	uint32_t reset_val;
+
+	REG_GET(DIG_FIFO_CTRL0, DIG_FIFO_ENABLE, &reset_val);
+	return (reset_val == 0) ? false : true;
+}
 void enc35_disable_fifo(struct stream_encoder *enc)
 {
 	struct dcn10_stream_encoder *enc1 = DCN10STRENC_FROM_STRENC(enc);
@@ -465,6 +473,7 @@ static const struct stream_encoder_funcs dcn35_str_enc_funcs = {
 	.set_input_mode = enc314_set_dig_input_mode,
 	.enable_fifo = enc35_enable_fifo,
 	.disable_fifo = enc35_disable_fifo,
+	.is_fifo_enabled = enc35_is_fifo_enabled,
 	.map_stream_to_link = enc35_stream_encoder_map_to_link,
 };
 

drivers/gpu/drm/amd/display/dc/inc/hw/stream_encoder.h

@@ -271,6 +271,7 @@ struct stream_encoder_funcs {
 		struct stream_encoder *enc, unsigned int pix_per_container);
 	void (*enable_fifo)(struct stream_encoder *enc);
 	void (*disable_fifo)(struct stream_encoder *enc);
+	bool (*is_fifo_enabled)(struct stream_encoder *enc);
 	void (*map_stream_to_link)(struct stream_encoder *enc, uint32_t stream_enc_inst, uint32_t link_enc_inst);
 };