drm/amd/display: Update DPPCLK programming sequence

[Description]
- When lowering DPPCLK, we want to program the DPP DTO before updating
the DPP refclk.
- Also update DPPCLK to the exact frequency that will be set after clock
divider has been programmed. This will prevent rounding errors when
making the request to PMFW (we need DPP DTO to match exactly with the
exact DPP refclk).
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c

@@ -325,6 +325,26 @@ static void dcn32_update_clocks_update_dtb_dto(struct clk_mgr_internal *clk_mgr,
 	}
 }
 
+/* Since DPPCLK request to PMFW needs to be exact (due to DPP DTO programming),
+ * update DPPCLK to be the exact frequency that will be set after the DPPCLK
+ * divider is updated. This will prevent rounding issues that could cause DPP
+ * refclk and DPP DTO to not match up.
+ */
+static void dcn32_update_dppclk_dispclk_freq(struct clk_mgr_internal *clk_mgr, struct dc_clocks *new_clocks)
+{
+	int dpp_divider = 0;
+	int disp_divider = 0;
+
+	dpp_divider = DENTIST_DIVIDER_RANGE_SCALE_FACTOR
+			* clk_mgr->base.dentist_vco_freq_khz / new_clocks->dppclk_khz;
+	disp_divider = DENTIST_DIVIDER_RANGE_SCALE_FACTOR
+			* clk_mgr->base.dentist_vco_freq_khz / new_clocks->dispclk_khz;
+
+	// Divide back the previous result to round up to the actual clock value that will be set from divider
+	new_clocks->dppclk_khz = (DENTIST_DIVIDER_RANGE_SCALE_FACTOR * clk_mgr->base.dentist_vco_freq_khz) / dpp_divider;
+	new_clocks->dispclk_khz = (DENTIST_DIVIDER_RANGE_SCALE_FACTOR * clk_mgr->base.dentist_vco_freq_khz) / disp_divider;
+}
+
 static void dcn32_update_clocks(struct clk_mgr *clk_mgr_base,
 			struct dc_state *context,
 			bool safe_to_lower)
@@ -448,13 +468,14 @@ static void dcn32_update_clocks(struct clk_mgr *clk_mgr_base,
 		}
 	}
 
+	dcn32_update_dppclk_dispclk_freq(clk_mgr, new_clocks);
 	if (should_set_clock(safe_to_lower, new_clocks->dppclk_khz, clk_mgr_base->clks.dppclk_khz)) {
 		if (clk_mgr_base->clks.dppclk_khz > new_clocks->dppclk_khz)
 			dpp_clock_lowered = true;
 
 		clk_mgr_base->clks.dppclk_khz = new_clocks->dppclk_khz;
 
-		if (clk_mgr->smu_present)
+		if (clk_mgr->smu_present && !dpp_clock_lowered)
 			dcn32_smu_set_hard_min_by_freq(clk_mgr, PPCLK_DPPCLK, khz_to_mhz_ceil(clk_mgr_base->clks.dppclk_khz));
 
 		update_dppclk = true;
@@ -488,6 +509,8 @@ static void dcn32_update_clocks(struct clk_mgr *clk_mgr_base,
 			/* if clock is being lowered, increase DTO before lowering refclk */
 			dcn20_update_clocks_update_dpp_dto(clk_mgr, context, safe_to_lower);
 			dcn20_update_clocks_update_dentist(clk_mgr, context);
+			if (clk_mgr->smu_present)
+				dcn32_smu_set_hard_min_by_freq(clk_mgr, PPCLK_DPPCLK, khz_to_mhz_ceil(clk_mgr_base->clks.dppclk_khz));
 		} else {
 			/* if clock is being raised, increase refclk before lowering DTO */
 			if (update_dppclk || update_dispclk)