drm/amd/display: Adjust dprefclk by down spread percentage.

[Why]
OLED panels show no display for large vtotal timings.

[How]
Check if ss is enabled and read from lut for spread spectrum percentage.
Adjust dprefclk as required. DP_DTO adjustment is for edp only.

Cc: stable@vger.kernel.org
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Zhongwei <zhongwei.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn35/dcn35_clk_mgr.c

@@ -73,6 +73,12 @@
 #define CLK1_CLK2_BYPASS_CNTL__CLK2_BYPASS_SEL_MASK		0x00000007L
 #define CLK1_CLK2_BYPASS_CNTL__CLK2_BYPASS_DIV_MASK		0x000F0000L
 
+#define regCLK5_0_CLK5_spll_field_8				0x464b
+#define regCLK5_0_CLK5_spll_field_8_BASE_IDX	0
+
+#define CLK5_0_CLK5_spll_field_8__spll_ssc_en__SHIFT	0xd
+#define CLK5_0_CLK5_spll_field_8__spll_ssc_en_MASK		0x00002000L
+
 #define SMU_VER_THRESHOLD 0x5D4A00 //93.74.0
 
 #define REG(reg_name) \
@@ -411,6 +417,17 @@ static void dcn35_dump_clk_registers(struct clk_state_registers_and_bypass *regs
 {
 }
 
+static bool dcn35_is_spll_ssc_enabled(struct clk_mgr *clk_mgr_base)
+{
+	struct clk_mgr_internal *clk_mgr = TO_CLK_MGR_INTERNAL(clk_mgr_base);
+	struct dc_context *ctx = clk_mgr->base.ctx;
+	uint32_t ssc_enable;
+
+	REG_GET(CLK5_0_CLK5_spll_field_8, spll_ssc_en, &ssc_enable);
+
+	return ssc_enable == 1;
+}
+
 static void init_clk_states(struct clk_mgr *clk_mgr)
 {
 	struct clk_mgr_internal *clk_mgr_int = TO_CLK_MGR_INTERNAL(clk_mgr);
@@ -428,7 +445,16 @@ static void init_clk_states(struct clk_mgr *clk_mgr)
 
 void dcn35_init_clocks(struct clk_mgr *clk_mgr)
 {
+	struct clk_mgr_internal *clk_mgr_int = TO_CLK_MGR_INTERNAL(clk_mgr);
 	init_clk_states(clk_mgr);
+
+	// to adjust dp_dto reference clock if ssc is enable otherwise to apply dprefclk
+	if (dcn35_is_spll_ssc_enabled(clk_mgr))
+		clk_mgr->dp_dto_source_clock_in_khz =
+			dce_adjust_dp_ref_freq_for_ss(clk_mgr_int, clk_mgr->dprefclk_khz);
+	else
+		clk_mgr->dp_dto_source_clock_in_khz = clk_mgr->dprefclk_khz;
+
 }
 static struct clk_bw_params dcn35_bw_params = {
 	.vram_type = Ddr4MemType,
@@ -517,6 +543,28 @@ static DpmClocks_t_dcn35 dummy_clocks;
 
 static struct dcn35_watermarks dummy_wms = { 0 };
 
+static struct dcn35_ss_info_table ss_info_table = {
+	.ss_divider = 1000,
+	.ss_percentage = {0, 0, 375, 375, 375}
+};
+
+static void dcn35_read_ss_info_from_lut(struct clk_mgr_internal *clk_mgr)
+{
+	struct dc_context *ctx = clk_mgr->base.ctx;
+	uint32_t clock_source;
+
+	REG_GET(CLK1_CLK2_BYPASS_CNTL, CLK2_BYPASS_SEL, &clock_source);
+	// If it's DFS mode, clock_source is 0.
+	if (dcn35_is_spll_ssc_enabled(&clk_mgr->base) && (clock_source < ARRAY_SIZE(ss_info_table.ss_percentage))) {
+		clk_mgr->dprefclk_ss_percentage = ss_info_table.ss_percentage[clock_source];
+
+		if (clk_mgr->dprefclk_ss_percentage != 0) {
+			clk_mgr->ss_on_dprefclk = true;
+			clk_mgr->dprefclk_ss_divider = ss_info_table.ss_divider;
+		}
+	}
+}
+
 static void dcn35_build_watermark_ranges(struct clk_bw_params *bw_params, struct dcn35_watermarks *table)
 {
 	int i, num_valid_sets;
@@ -1061,6 +1109,8 @@ void dcn35_clk_mgr_construct(
 	dce_clock_read_ss_info(&clk_mgr->base);
 	/*when clk src is from FCH, it could have ss, same clock src as DPREF clk*/
 
+	dcn35_read_ss_info_from_lut(&clk_mgr->base);
+
 	clk_mgr->base.base.bw_params = &dcn35_bw_params;
 
 	if (clk_mgr->base.base.ctx->dc->debug.pstate_enabled) {

drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c

@@ -976,7 +976,10 @@ static bool dcn31_program_pix_clk(
 	struct bp_pixel_clock_parameters bp_pc_params = {0};
 	enum transmitter_color_depth bp_pc_colour_depth = TRANSMITTER_COLOR_DEPTH_24;
 
-	if (clock_source->ctx->dc->clk_mgr->dp_dto_source_clock_in_khz != 0)
+	// Apply ssed(spread spectrum) dpref clock for edp only.
+	if (clock_source->ctx->dc->clk_mgr->dp_dto_source_clock_in_khz != 0
+		&& pix_clk_params->signal_type == SIGNAL_TYPE_EDP
+		&& encoding == DP_8b_10b_ENCODING)
 		dp_dto_ref_khz = clock_source->ctx->dc->clk_mgr->dp_dto_source_clock_in_khz;
 	// For these signal types Driver to program DP_DTO without calling VBIOS Command table
 	if (dc_is_dp_signal(pix_clk_params->signal_type) || dc_is_virtual_signal(pix_clk_params->signal_type)) {
@@ -1093,9 +1096,6 @@ static bool get_pixel_clk_frequency_100hz(
 	unsigned int modulo_hz = 0;
 	unsigned int dp_dto_ref_khz = clock_source->ctx->dc->clk_mgr->dprefclk_khz;
 
-	if (clock_source->ctx->dc->clk_mgr->dp_dto_source_clock_in_khz != 0)
-		dp_dto_ref_khz = clock_source->ctx->dc->clk_mgr->dp_dto_source_clock_in_khz;
-
 	if (clock_source->id == CLOCK_SOURCE_ID_DP_DTO) {
 		clock_hz = REG_READ(PHASE[inst]);