drm/amd/display: DCN35 set min dispclk to 50Mhz

[Why]

Causes hard hangs when resuming after display off on extended/duplicate
modes

[How]

Set the min dispclk to 50Mhz for DCN35
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Nicholas Susanto <Nicholas.Susanto@amd.com>
Signed-off-by: Roman Li <roman.li@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

@@ -305,6 +305,9 @@ void dcn35_update_clocks(struct clk_mgr *clk_mgr_base,
 	if (new_clocks->dtbclk_en && !new_clocks->ref_dtbclk_khz)
 		new_clocks->ref_dtbclk_khz = 600000;
 
+	if (dc->debug.min_disp_clk_khz > 0 && new_clocks->dispclk_khz < dc->debug.min_disp_clk_khz)
+		new_clocks->dispclk_khz = dc->debug.min_disp_clk_khz;
+
 	/*
 	 * if it is safe to lower, but we are already in the lower state, we don't have to do anything
 	 * also if safe to lower is false, we just go in the higher state

drivers/gpu/drm/amd/display/dc/resource/dcn35/dcn35_resource.c

@@ -786,6 +786,7 @@ static const struct dc_debug_options debug_defaults_drv = {
 	.disable_dmub_reallow_idle = false,
 	.static_screen_wait_frames = 2,
 	.disable_timeout = true,
+	.min_disp_clk_khz = 50000,
 };
 
 static const struct dc_panel_config panel_config_defaults = {