drm/amd/display: add support for forcing DCFCLK without affecting watermarks

[why]
useful for debugging

[how]
plumb a debug option in dc
Signed-off-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn20/dcn20_clk_mgr.c

@@ -172,6 +172,10 @@ void dcn2_update_clocks(struct clk_mgr *clk_mgr_base,
 			pp_smu->set_voltage_by_freq(&pp_smu->pp_smu, PP_SMU_NV_PHYCLK, clk_mgr_base->clks.phyclk_khz / 1000);
 	}
 
+	if (dc->debug.force_min_dcfclk_mhz > 0)
+		new_clocks->dcfclk_khz = (new_clocks->dcfclk_khz > (dc->debug.force_min_dcfclk_mhz * 1000)) ?
+				new_clocks->dcfclk_khz : (dc->debug.force_min_dcfclk_mhz * 1000);
+
 	if (should_set_clock(safe_to_lower, new_clocks->dcfclk_khz, clk_mgr_base->clks.dcfclk_khz)) {
 		clk_mgr_base->clks.dcfclk_khz = new_clocks->dcfclk_khz;
 		if (pp_smu && pp_smu->set_hard_min_dcfclk_by_freq)

drivers/gpu/drm/amd/display/dc/dc.h

@@ -369,6 +369,10 @@ struct dc_debug_options {
 #ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
 	bool disable_fec;
 #endif
+	/* This forces a hard min on the DCFCLK requested to SMU/PP
+	 * watermarks are not affected.
+	 */
+	unsigned int force_min_dcfclk_mhz;
 };
 
 struct dc_debug_data {
@@ -418,6 +422,10 @@ struct dc_bounding_box_overrides {
 	int urgent_latency_ns;
 	int percent_of_ideal_drambw;
 	int dram_clock_change_latency_ns;
+	/* This forces a hard min on the DCFCLK we use
+	 * for DML.  Unlike the debug option for forcing
+	 * DCFCLK, this override affects watermark calculations
+	 */
 	int min_dcfclk_mhz;
 };