drm/amd/display: w/a to program DISPCLK_R_GATE_DISABLE DCN35

[WHY & HOW]
Cursor corruption observed on USBC display with specific system setup with a
reboot. Cursor memory might still in the lightsleep state due to voltage
issue, we need program DISPCLK_R_GATE_DISABLE to avoid this issue only on
DCN35.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Yihan Zhu <Yihan.Zhu@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@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/dpp/dcn20/dcn20_dpp.h

@@ -690,6 +690,7 @@ struct dcn20_dpp {
 	int lb_memory_size;
 	int lb_bits_per_entry;
 	bool is_write_to_ram_a_safe;
+	bool dispclk_r_gate_disable;
 	struct scaler_data scl_data;
 	struct pwl_params pwl_data;
 };

drivers/gpu/drm/amd/display/dc/dpp/dcn30/dcn30_dpp.h

@@ -572,6 +572,7 @@ struct dcn3_dpp {
 	int lb_memory_size;
 	int lb_bits_per_entry;
 	bool is_write_to_ram_a_safe;
+	bool dispclk_r_gate_disable;
 	struct scaler_data scl_data;
 	struct pwl_params pwl_data;
 };

drivers/gpu/drm/amd/display/dc/dpp/dcn35/dcn35_dpp.c

@@ -50,11 +50,21 @@ void dpp35_dppclk_control(
 				DPPCLK_RATE_CONTROL, dppclk_div,
 				DPP_CLOCK_ENABLE, 1);
 		else
-			REG_UPDATE(DPP_CONTROL,
-					DPP_CLOCK_ENABLE, 1);
+			if (dpp->dispclk_r_gate_disable)
+				REG_UPDATE_2(DPP_CONTROL,
+					DPP_CLOCK_ENABLE, 1,
+					DISPCLK_R_GATE_DISABLE, 1);
+			else
+				REG_UPDATE(DPP_CONTROL,
+						DPP_CLOCK_ENABLE, 1);
 	} else
-		REG_UPDATE(DPP_CONTROL,
-				DPP_CLOCK_ENABLE, 0);
+		if (dpp->dispclk_r_gate_disable)
+			REG_UPDATE_2(DPP_CONTROL,
+				DPP_CLOCK_ENABLE, 0,
+				DISPCLK_R_GATE_DISABLE, 0);
+		else
+			REG_UPDATE(DPP_CONTROL,
+					DPP_CLOCK_ENABLE, 0);
 }
 
 void dpp35_program_bias_and_scale_fcnv(
@@ -126,6 +136,10 @@ bool dpp35_construct(
 			      (const struct dcn3_dpp_mask *)(tf_mask));
 
 	dpp->base.funcs = &dcn35_dpp_funcs;
+
+	// w/a for cursor memory stuck in LS by programming DISPCLK_R_GATE_DISABLE, limit w/a to some ASIC revs
+	if (dpp->base.ctx->asic_id.hw_internal_rev <= 0x10)
+		dpp->dispclk_r_gate_disable = true;
 	return ret;
 }