drm/radeon/kms/atom: add support for spread spectrum (v2)

Spread spectrum is a periodic disturbance added
to the feedback divider to change the pixel clock
periodically to reduce interference.

Only enabled on LVDS.

v2: add support for r4xx and fix DCE 3
Signed-off-by: NAlex Deucher <alexdeucher@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/atombios.h

@@ -2314,7 +2314,7 @@ typedef struct _ATOM_SPREAD_SPECTRUM_ASSIGNMENT {
 	UCHAR ucSS_Step;
 	UCHAR ucSS_Delay;
 	UCHAR ucSS_Id;
-	UCHAR ucRecommandedRef_Div;
+	UCHAR ucRecommendedRef_Div;
 	UCHAR ucSS_Range;	/* it was reserved for V11 */
 } ATOM_SPREAD_SPECTRUM_ASSIGNMENT;
 

drivers/gpu/drm/radeon/atombios_crtc.c

@@ -351,6 +351,61 @@ static void atombios_crtc_set_timing(struct drm_crtc *crtc,
 	atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);
 }
 
+static void atombios_set_ss(struct drm_crtc *crtc, int enable)
+{
+	struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
+	struct drm_device *dev = crtc->dev;
+	struct radeon_device *rdev = dev->dev_private;
+	struct drm_encoder *encoder = NULL;
+	struct radeon_encoder *radeon_encoder = NULL;
+	struct radeon_encoder_atom_dig *dig = NULL;
+	int index = GetIndexIntoMasterTable(COMMAND, EnableSpreadSpectrumOnPPLL);
+	ENABLE_SPREAD_SPECTRUM_ON_PPLL_PS_ALLOCATION args;
+	ENABLE_LVDS_SS_PARAMETERS legacy_args;
+	uint16_t percentage = 0;
+	uint8_t type = 0, step = 0, delay = 0, range = 0;
+
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+		if (encoder->crtc == crtc) {
+			radeon_encoder = to_radeon_encoder(encoder);
+			dig = radeon_encoder->enc_priv;
+			/* only enable spread spectrum on LVDS */
+			if (dig && dig->ss) {
+				percentage = dig->ss->percentage;
+				type = dig->ss->type;
+				step = dig->ss->step;
+				delay = dig->ss->delay;
+				range = dig->ss->range;
+			} else if (enable)
+				return;
+			break;
+		}
+	}
+
+	if (!radeon_encoder)
+		return;
+
+	if (ASIC_IS_AVIVO(rdev)) {
+		memset(&args, 0, sizeof(args));
+		args.usSpreadSpectrumPercentage = percentage;
+		args.ucSpreadSpectrumType = type;
+		args.ucSpreadSpectrumStep = step;
+		args.ucSpreadSpectrumDelay = delay;
+		args.ucSpreadSpectrumRange = range;
+		args.ucPpll = radeon_crtc->crtc_id ? ATOM_PPLL2 : ATOM_PPLL1;
+		args.ucEnable = enable;
+		atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);
+	} else {
+		memset(&legacy_args, 0, sizeof(legacy_args));
+		legacy_args.usSpreadSpectrumPercentage = percentage;
+		legacy_args.ucSpreadSpectrumType = type;
+		legacy_args.ucSpreadSpectrumStepSize_Delay = (step & 3) << 2;
+		legacy_args.ucSpreadSpectrumStepSize_Delay |= (delay & 7) << 4;
+		legacy_args.ucEnable = enable;
+		atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&legacy_args);
+	}
+}
+
 void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode *mode)
 {
 	struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
@@ -373,8 +428,6 @@ void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode *mode)
 	memset(&args, 0, sizeof(args));
 
 	if (ASIC_IS_AVIVO(rdev)) {
-		uint32_t ss_cntl;
-
 		if ((rdev->family == CHIP_RS600) ||
 		    (rdev->family == CHIP_RS690) ||
 		    (rdev->family == CHIP_RS740))
@@ -385,15 +438,6 @@ void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode *mode)
 			pll_flags |= RADEON_PLL_PREFER_HIGH_FB_DIV;
 		else
 			pll_flags |= RADEON_PLL_PREFER_LOW_REF_DIV;
-
-		/* disable spread spectrum clocking for now -- thanks Hedy Lamarr */
-		if (radeon_crtc->crtc_id == 0) {
-			ss_cntl = RREG32(AVIVO_P1PLL_INT_SS_CNTL);
-			WREG32(AVIVO_P1PLL_INT_SS_CNTL, ss_cntl & ~1);
-		} else {
-			ss_cntl = RREG32(AVIVO_P2PLL_INT_SS_CNTL);
-			WREG32(AVIVO_P2PLL_INT_SS_CNTL, ss_cntl & ~1);
-		}
 	} else {
 		pll_flags |= RADEON_PLL_LEGACY;
 
@@ -641,7 +685,9 @@ int atombios_crtc_mode_set(struct drm_crtc *crtc,
 
 	/* TODO color tiling */
 
+	atombios_set_ss(crtc, 0);
 	atombios_crtc_set_pll(crtc, adjusted_mode);
+	atombios_set_ss(crtc, 1);
 	atombios_crtc_set_timing(crtc, adjusted_mode);
 
 	if (ASIC_IS_AVIVO(rdev))

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -771,6 +771,46 @@ bool radeon_atombios_get_tmds_info(struct radeon_encoder *encoder,
 	return false;
 }
 
+static struct radeon_atom_ss *radeon_atombios_get_ss_info(struct
+							  radeon_encoder
+							  *encoder,
+							  int id)
+{
+	struct drm_device *dev = encoder->base.dev;
+	struct radeon_device *rdev = dev->dev_private;
+	struct radeon_mode_info *mode_info = &rdev->mode_info;
+	int index = GetIndexIntoMasterTable(DATA, PPLL_SS_Info);
+	uint16_t data_offset;
+	struct _ATOM_SPREAD_SPECTRUM_INFO *ss_info;
+	uint8_t frev, crev;
+	struct radeon_atom_ss *ss = NULL;
+
+	if (id > ATOM_MAX_SS_ENTRY)
+		return NULL;
+
+	atom_parse_data_header(mode_info->atom_context, index, NULL, &frev,
+			       &crev, &data_offset);
+
+	ss_info =
+	    (struct _ATOM_SPREAD_SPECTRUM_INFO *)(mode_info->atom_context->bios + data_offset);
+
+	if (ss_info) {
+		ss =
+		    kzalloc(sizeof(struct radeon_atom_ss), GFP_KERNEL);
+
+		if (!ss)
+			return NULL;
+
+		ss->percentage = le16_to_cpu(ss_info->asSS_Info[id].usSpreadSpectrumPercentage);
+		ss->type = ss_info->asSS_Info[id].ucSpreadSpectrumType;
+		ss->step = ss_info->asSS_Info[id].ucSS_Step;
+		ss->delay = ss_info->asSS_Info[id].ucSS_Delay;
+		ss->range = ss_info->asSS_Info[id].ucSS_Range;
+		ss->refdiv = ss_info->asSS_Info[id].ucRecommendedRef_Div;
+	}
+	return ss;
+}
+
 union lvds_info {
 	struct _ATOM_LVDS_INFO info;
 	struct _ATOM_LVDS_INFO_V12 info_12;
@@ -826,6 +866,8 @@ struct radeon_encoder_atom_dig *radeon_atombios_get_lvds_info(struct
 		/* set crtc values */
 		drm_mode_set_crtcinfo(&lvds->native_mode, CRTC_INTERLACE_HALVE_V);
 
+		lvds->ss = radeon_atombios_get_ss_info(encoder, lvds_info->info.ucSS_Id);
+
 		encoder->native_mode = lvds->native_mode;
 	}
 	return lvds;

drivers/gpu/drm/radeon/radeon_mode.h

@@ -260,6 +260,16 @@ struct radeon_encoder_int_tmds {
 	struct radeon_tmds_pll tmds_pll[4];
 };
 
+/* spread spectrum */
+struct radeon_atom_ss {
+	uint16_t percentage;
+	uint8_t type;
+	uint8_t step;
+	uint8_t delay;
+	uint8_t range;
+	uint8_t refdiv;
+};
+
 struct radeon_encoder_atom_dig {
 	/* atom dig */
 	bool coherent_mode;
@@ -267,6 +277,7 @@ struct radeon_encoder_atom_dig {
 	/* atom lvds */
 	uint32_t lvds_misc;
 	uint16_t panel_pwr_delay;
+	struct radeon_atom_ss *ss;
 	/* panel mode */
 	struct drm_display_mode native_mode;
 };