drm/radeon: handle ss percentage divider properly

It's either 100 or 1000 depending on the flags in the
table.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/atombios_crtc.c

@@ -1042,15 +1042,17 @@ static void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode
 		/* calculate ss amount and step size */
 		if (ASIC_IS_DCE4(rdev)) {
 			u32 step_size;
-			u32 amount = (((fb_div * 10) + frac_fb_div) * radeon_crtc->ss.percentage) / 10000;
+			u32 amount = (((fb_div * 10) + frac_fb_div) *
+				      (u32)radeon_crtc->ss.percentage) /
+				(100 * (u32)radeon_crtc->ss.percentage_divider);
 			radeon_crtc->ss.amount = (amount / 10) & ATOM_PPLL_SS_AMOUNT_V2_FBDIV_MASK;
 			radeon_crtc->ss.amount |= ((amount - (amount / 10)) << ATOM_PPLL_SS_AMOUNT_V2_NFRAC_SHIFT) &
 				ATOM_PPLL_SS_AMOUNT_V2_NFRAC_MASK;
 			if (radeon_crtc->ss.type & ATOM_PPLL_SS_TYPE_V2_CENTRE_SPREAD)
-				step_size = (4 * amount * ref_div * (radeon_crtc->ss.rate * 2048)) /
+				step_size = (4 * amount * ref_div * ((u32)radeon_crtc->ss.rate * 2048)) /
 					(125 * 25 * pll->reference_freq / 100);
 			else
-				step_size = (2 * amount * ref_div * (radeon_crtc->ss.rate * 2048)) /
+				step_size = (2 * amount * ref_div * ((u32)radeon_crtc->ss.rate * 2048)) /
 					(125 * 25 * pll->reference_freq / 100);
 			radeon_crtc->ss.step = step_size;
 		}

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -1511,6 +1511,7 @@ bool radeon_atombios_get_asic_ss_info(struct radeon_device *rdev,
 						le16_to_cpu(ss_assign->v1.usSpreadSpectrumPercentage);
 					ss->type = ss_assign->v1.ucSpreadSpectrumMode;
 					ss->rate = le16_to_cpu(ss_assign->v1.usSpreadRateInKhz);
+					ss->percentage_divider = 100;
 					return true;
 				}
 				ss_assign = (union asic_ss_assignment *)
@@ -1528,6 +1529,7 @@ bool radeon_atombios_get_asic_ss_info(struct radeon_device *rdev,
 						le16_to_cpu(ss_assign->v2.usSpreadSpectrumPercentage);
 					ss->type = ss_assign->v2.ucSpreadSpectrumMode;
 					ss->rate = le16_to_cpu(ss_assign->v2.usSpreadRateIn10Hz);
+					ss->percentage_divider = 100;
 					if ((crev == 2) &&
 					    ((id == ASIC_INTERNAL_ENGINE_SS) ||
 					     (id == ASIC_INTERNAL_MEMORY_SS)))
@@ -1549,6 +1551,11 @@ bool radeon_atombios_get_asic_ss_info(struct radeon_device *rdev,
 						le16_to_cpu(ss_assign->v3.usSpreadSpectrumPercentage);
 					ss->type = ss_assign->v3.ucSpreadSpectrumMode;
 					ss->rate = le16_to_cpu(ss_assign->v3.usSpreadRateIn10Hz);
+					if (ss_assign->v3.ucSpreadSpectrumMode &
+					    SS_MODE_V3_PERCENTAGE_DIV_BY_1000_MASK)
+						ss->percentage_divider = 1000;
+					else
+						ss->percentage_divider = 100;
 					if ((id == ASIC_INTERNAL_ENGINE_SS) ||
 					    (id == ASIC_INTERNAL_MEMORY_SS))
 						ss->rate /= 100;

drivers/gpu/drm/radeon/radeon_mode.h

@@ -291,6 +291,7 @@ struct radeon_tv_regs {
 
 struct radeon_atom_ss {
 	uint16_t percentage;
+	uint16_t percentage_divider;
 	uint8_t type;
 	uint16_t step;
 	uint8_t delay;