drm/radeon/kms/atom: spread spectrum fix

The atom spread spectrum table does not always
disable ss.  Explicitly disable it and then use
the atom table to enable later if needed (currently
only used for LVDS).

Fixes display issues on some systems.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/atombios_crtc.c

@@ -353,12 +353,55 @@ 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_disable_ss(struct drm_crtc *crtc)
+{
+	struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
+	struct drm_device *dev = crtc->dev;
+	struct radeon_device *rdev = dev->dev_private;
+	u32 ss_cntl;
+
+	if (ASIC_IS_DCE4(rdev)) {
+		switch (radeon_crtc->pll_id) {
+		case ATOM_PPLL1:
+			ss_cntl = RREG32(EVERGREEN_P1PLL_SS_CNTL);
+			ss_cntl &= ~EVERGREEN_PxPLL_SS_EN;
+			WREG32(EVERGREEN_P1PLL_SS_CNTL, ss_cntl);
+			break;
+		case ATOM_PPLL2:
+			ss_cntl = RREG32(EVERGREEN_P2PLL_SS_CNTL);
+			ss_cntl &= ~EVERGREEN_PxPLL_SS_EN;
+			WREG32(EVERGREEN_P2PLL_SS_CNTL, ss_cntl);
+			break;
+		case ATOM_DCPLL:
+		case ATOM_PPLL_INVALID:
+			return;
+		}
+	} else if (ASIC_IS_AVIVO(rdev)) {
+		switch (radeon_crtc->pll_id) {
+		case ATOM_PPLL1:
+			ss_cntl = RREG32(AVIVO_P1PLL_INT_SS_CNTL);
+			ss_cntl &= ~1;
+			WREG32(AVIVO_P1PLL_INT_SS_CNTL, ss_cntl);
+			break;
+		case ATOM_PPLL2:
+			ss_cntl = RREG32(AVIVO_P2PLL_INT_SS_CNTL);
+			ss_cntl &= ~1;
+			WREG32(AVIVO_P2PLL_INT_SS_CNTL, ss_cntl);
+			break;
+		case ATOM_DCPLL:
+		case ATOM_PPLL_INVALID:
+			return;
+		}
+	}
+}
+
+
 union atom_enable_ss {
 	ENABLE_LVDS_SS_PARAMETERS legacy;
 	ENABLE_SPREAD_SPECTRUM_ON_PPLL_PS_ALLOCATION v1;
 };
 
-static void atombios_set_ss(struct drm_crtc *crtc, int enable)
+static void atombios_enable_ss(struct drm_crtc *crtc)
 {
 	struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
 	struct drm_device *dev = crtc->dev;
@@ -387,9 +430,9 @@ static void atombios_set_ss(struct drm_crtc *crtc, int enable)
 					step = dig->ss->step;
 					delay = dig->ss->delay;
 					range = dig->ss->range;
-				} else if (enable)
+				} else
 					return;
-			} else if (enable)
+			} else
 				return;
 			break;
 		}
@@ -406,13 +449,13 @@ static void atombios_set_ss(struct drm_crtc *crtc, int enable)
 		args.v1.ucSpreadSpectrumDelay = delay;
 		args.v1.ucSpreadSpectrumRange = range;
 		args.v1.ucPpll = radeon_crtc->crtc_id ? ATOM_PPLL2 : ATOM_PPLL1;
-		args.v1.ucEnable = enable;
+		args.v1.ucEnable = ATOM_ENABLE;
 	} else {
 		args.legacy.usSpreadSpectrumPercentage = cpu_to_le16(percentage);
 		args.legacy.ucSpreadSpectrumType = type;
 		args.legacy.ucSpreadSpectrumStepSize_Delay = (step & 3) << 2;
 		args.legacy.ucSpreadSpectrumStepSize_Delay |= (delay & 7) << 4;
-		args.legacy.ucEnable = enable;
+		args.legacy.ucEnable = ATOM_ENABLE;
 	}
 	atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);
 }
@@ -1086,12 +1129,12 @@ int atombios_crtc_mode_set(struct drm_crtc *crtc,
 	/* pick pll */
 	radeon_crtc->pll_id = radeon_atom_pick_pll(crtc);
 
-	atombios_set_ss(crtc, 0);
+	atombios_disable_ss(crtc);
 	/* always set DCPLL */
 	if (ASIC_IS_DCE4(rdev))
 		atombios_crtc_set_dcpll(crtc);
 	atombios_crtc_set_pll(crtc, adjusted_mode);
-	atombios_set_ss(crtc, 1);
+	atombios_enable_ss(crtc);
 
 	if (ASIC_IS_DCE4(rdev))
 		atombios_set_crtc_dtd_timing(crtc, adjusted_mode);