drm/amd/display: Implement workaround for writing to OTG_PIXEL_RATE_DIV register

[Why and How]
Current implementation requires FPGA builds to take a different
code path from DCN32 to write to OTG_PIXEL_RATE_DIV. Now that
we have a workaround to write to OTG_PIXEL_RATE_DIV register without
blanking display on hotplug on DCN32, we can allow the code paths for
FPGA to be exactly the same allowing for more consistent
testing.
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Saaem Rizvi <SyedSaaem.Rizvi@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/dcn20/dcn20_dccg.h

@@ -230,7 +230,8 @@
 	type DTBCLK_P2_SRC_SEL;\
 	type DTBCLK_P2_EN;\
 	type DTBCLK_P3_SRC_SEL;\
-	type DTBCLK_P3_EN;
+	type DTBCLK_P3_EN;\
+	type DENTIST_DISPCLK_CHG_DONE;
 
 struct dccg_shift {
 	DCCG_REG_FIELD_LIST(uint8_t)

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c

@@ -42,6 +42,20 @@
 #define DC_LOGGER \
 	dccg->ctx->logger
 
+/* This function is a workaround for writing to OTG_PIXEL_RATE_DIV
+ * without the probability of causing a DIG FIFO error.
+ */
+static void dccg32_wait_for_dentist_change_done(
+	struct dccg *dccg)
+{
+	struct dcn_dccg *dccg_dcn = TO_DCN_DCCG(dccg);
+
+	uint32_t dentist_dispclk_value = REG_READ(DENTIST_DISPCLK_CNTL);
+
+	REG_WRITE(DENTIST_DISPCLK_CNTL, dentist_dispclk_value);
+	REG_WAIT(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_CHG_DONE, 1, 50, 2000);
+}
+
 static void dccg32_get_pixel_rate_div(
 		struct dccg *dccg,
 		uint32_t otg_inst,
@@ -110,21 +124,29 @@ static void dccg32_set_pixel_rate_div(
 		REG_UPDATE_2(OTG_PIXEL_RATE_DIV,
 				OTG0_PIXEL_RATE_DIVK1, k1,
 				OTG0_PIXEL_RATE_DIVK2, k2);
+
+		dccg32_wait_for_dentist_change_done(dccg);
 		break;
 	case 1:
 		REG_UPDATE_2(OTG_PIXEL_RATE_DIV,
 				OTG1_PIXEL_RATE_DIVK1, k1,
 				OTG1_PIXEL_RATE_DIVK2, k2);
+
+		dccg32_wait_for_dentist_change_done(dccg);
 		break;
 	case 2:
 		REG_UPDATE_2(OTG_PIXEL_RATE_DIV,
 				OTG2_PIXEL_RATE_DIVK1, k1,
 				OTG2_PIXEL_RATE_DIVK2, k2);
+
+		dccg32_wait_for_dentist_change_done(dccg);
 		break;
 	case 3:
 		REG_UPDATE_2(OTG_PIXEL_RATE_DIV,
 				OTG3_PIXEL_RATE_DIVK1, k1,
 				OTG3_PIXEL_RATE_DIVK2, k2);
+
+		dccg32_wait_for_dentist_change_done(dccg);
 		break;
 	default:
 		BREAK_TO_DEBUGGER();

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.h

@@ -111,7 +111,8 @@
 	DCCG_SF(DTBCLK_P_CNTL, DTBCLK_P3_SRC_SEL, mask_sh),\
 	DCCG_SF(DTBCLK_P_CNTL, DTBCLK_P3_EN, mask_sh),\
 	DCCG_SF(DCCG_AUDIO_DTO_SOURCE, DCCG_AUDIO_DTO_SEL, mask_sh),\
-	DCCG_SF(DCCG_AUDIO_DTO_SOURCE, DCCG_AUDIO_DTO0_SOURCE_SEL, mask_sh)
+	DCCG_SF(DCCG_AUDIO_DTO_SOURCE, DCCG_AUDIO_DTO0_SOURCE_SEL, mask_sh),\
+	DCCG_SF(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_CHG_DONE, mask_sh)
 
 
 struct dccg *dccg32_create(

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c

@@ -1111,7 +1111,7 @@ unsigned int dcn32_calculate_dccg_k1_k2_values(struct pipe_ctx *pipe_ctx, unsign
 			*k2_div = PIXEL_RATE_DIV_BY_2;
 		else
 			*k2_div = PIXEL_RATE_DIV_BY_4;
-	} else if (dc_is_dp_signal(stream->signal)) {
+	} else if (dc_is_dp_signal(stream->signal) || dc_is_virtual_signal(stream->signal)) {
 		if (two_pix_per_container) {
 			*k1_div = PIXEL_RATE_DIV_BY_1;
 			*k2_div = PIXEL_RATE_DIV_BY_2;

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.h

@@ -1276,7 +1276,8 @@ double dcn32_determine_max_vratio_prefetch(struct dc *dc, struct dc_state *conte
       DCCG_SRII(PHASE, DTBCLK_DTO, 0), DCCG_SRII(PHASE, DTBCLK_DTO, 1),        \
       DCCG_SRII(PHASE, DTBCLK_DTO, 2), DCCG_SRII(PHASE, DTBCLK_DTO, 3),        \
       SR(DCCG_AUDIO_DTBCLK_DTO_MODULO), SR(DCCG_AUDIO_DTBCLK_DTO_PHASE),       \
-      SR(OTG_PIXEL_RATE_DIV), SR(DTBCLK_P_CNTL), SR(DCCG_AUDIO_DTO_SOURCE)     \
+      SR(OTG_PIXEL_RATE_DIV), SR(DTBCLK_P_CNTL),                               \
+      SR(DCCG_AUDIO_DTO_SOURCE), SR(DENTIST_DISPCLK_CNTL)                      \
   )
 
 /* VMID */