diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index b8c0ebd50889..506e6896f8ea 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -9005,6 +9005,7 @@ enum skl_power_gate {
 #define _MG_REFCLKIN_CTL_PORT3				0x16A92C
 #define _MG_REFCLKIN_CTL_PORT4				0x16B92C
 #define   MG_REFCLKIN_CTL_OD_2_MUX(x)			((x) << 8)
+#define   MG_REFCLKIN_CTL_OD_2_MUX_MASK			(0x7 << 8)
 #define MG_REFCLKIN_CTL(port) _MMIO_PORT((port) - PORT_C, \
 					 _MG_REFCLKIN_CTL_PORT1, \
 					 _MG_REFCLKIN_CTL_PORT2)
@@ -9014,7 +9015,9 @@ enum skl_power_gate {
 #define _MG_CLKTOP2_CORECLKCTL1_PORT3			0x16A8D8
 #define _MG_CLKTOP2_CORECLKCTL1_PORT4			0x16B8D8
 #define   MG_CLKTOP2_CORECLKCTL1_B_DIVRATIO(x)		((x) << 16)
+#define   MG_CLKTOP2_CORECLKCTL1_B_DIVRATIO_MASK	(0xff << 16)
 #define   MG_CLKTOP2_CORECLKCTL1_A_DIVRATIO(x)		((x) << 8)
+#define   MG_CLKTOP2_CORECLKCTL1_A_DIVRATIO_MASK	(0xff << 8)
 #define MG_CLKTOP2_CORECLKCTL1(port) _MMIO_PORT((port) - PORT_C, \
 						_MG_CLKTOP2_CORECLKCTL1_PORT1, \
 						_MG_CLKTOP2_CORECLKCTL1_PORT2)
@@ -9024,9 +9027,13 @@ enum skl_power_gate {
 #define _MG_CLKTOP2_HSCLKCTL_PORT3			0x16A8D4
 #define _MG_CLKTOP2_HSCLKCTL_PORT4			0x16B8D4
 #define   MG_CLKTOP2_HSCLKCTL_CORE_INPUTSEL(x)		((x) << 16)
+#define   MG_CLKTOP2_HSCLKCTL_CORE_INPUTSEL_MASK	(0x1 << 16)
 #define   MG_CLKTOP2_HSCLKCTL_TLINEDRV_CLKSEL(x)	((x) << 14)
+#define   MG_CLKTOP2_HSCLKCTL_TLINEDRV_CLKSEL_MASK	(0x3 << 14)
 #define   MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO(x)		((x) << 12)
+#define   MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_MASK		(0x3 << 12)
 #define   MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO(x)		((x) << 8)
+#define   MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_MASK		(0xf << 8)
 #define MG_CLKTOP2_HSCLKCTL(port) _MMIO_PORT((port) - PORT_C, \
 					     _MG_CLKTOP2_HSCLKCTL_PORT1, \
 					     _MG_CLKTOP2_HSCLKCTL_PORT2)
@@ -9100,12 +9107,18 @@ enum skl_power_gate {
 #define _MG_PLL_BIAS_PORT3				0x16AA14
 #define _MG_PLL_BIAS_PORT4				0x16BA14
 #define   MG_PLL_BIAS_BIAS_GB_SEL(x)			((x) << 30)
+#define   MG_PLL_BIAS_BIAS_GB_SEL_MASK			(0x3 << 30)
 #define   MG_PLL_BIAS_INIT_DCOAMP(x)			((x) << 24)
+#define   MG_PLL_BIAS_INIT_DCOAMP_MASK			(0x3f << 24)
 #define   MG_PLL_BIAS_BIAS_BONUS(x)			((x) << 16)
+#define   MG_PLL_BIAS_BIAS_BONUS_MASK			(0xff << 16)
 #define   MG_PLL_BIAS_BIASCAL_EN			(1 << 15)
 #define   MG_PLL_BIAS_CTRIM(x)				((x) << 8)
+#define   MG_PLL_BIAS_CTRIM_MASK			(0x1f << 8)
 #define   MG_PLL_BIAS_VREF_RDAC(x)			((x) << 5)
+#define   MG_PLL_BIAS_VREF_RDAC_MASK			(0x7 << 5)
 #define   MG_PLL_BIAS_IREFTRIM(x)			((x) << 0)
+#define   MG_PLL_BIAS_IREFTRIM_MASK			(0x1f << 0)
 #define MG_PLL_BIAS(port) _MMIO_PORT((port) - PORT_C, _MG_PLL_BIAS_PORT1, \
 				     _MG_PLL_BIAS_PORT2)
 
diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
index d4c7bacbe83e..3ffc219a2407 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
@@ -2945,10 +2945,21 @@ static bool icl_pll_get_hw_state(struct drm_i915_private *dev_priv,
 	case DPLL_ID_ICL_MGPLL4:
 		port = icl_mg_pll_id_to_port(id);
 		hw_state->mg_refclkin_ctl = I915_READ(MG_REFCLKIN_CTL(port));
+		hw_state->mg_refclkin_ctl &= MG_REFCLKIN_CTL_OD_2_MUX_MASK;
+
 		hw_state->mg_clktop2_coreclkctl1 =
 			I915_READ(MG_CLKTOP2_CORECLKCTL1(port));
+		hw_state->mg_clktop2_coreclkctl1 &=
+			MG_CLKTOP2_CORECLKCTL1_A_DIVRATIO_MASK;
+
 		hw_state->mg_clktop2_hsclkctl =
 			I915_READ(MG_CLKTOP2_HSCLKCTL(port));
+		hw_state->mg_clktop2_hsclkctl &= (
+			MG_CLKTOP2_HSCLKCTL_TLINEDRV_CLKSEL_MASK |
+			MG_CLKTOP2_HSCLKCTL_CORE_INPUTSEL_MASK |
+			MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_MASK |
+			MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_MASK);
+
 		hw_state->mg_pll_div0 = I915_READ(MG_PLL_DIV0(port));
 		hw_state->mg_pll_div1 = I915_READ(MG_PLL_DIV1(port));
 		hw_state->mg_pll_lf = I915_READ(MG_PLL_LF(port));
@@ -2998,10 +3009,24 @@ static void icl_mg_pll_write(struct drm_i915_private *dev_priv,
 	enum port port = icl_mg_pll_id_to_port(pll->info->id);
 	u32 val;
 
-	I915_WRITE(MG_REFCLKIN_CTL(port), hw_state->mg_refclkin_ctl);
-	I915_WRITE(MG_CLKTOP2_CORECLKCTL1(port),
-		   hw_state->mg_clktop2_coreclkctl1);
-	I915_WRITE(MG_CLKTOP2_HSCLKCTL(port), hw_state->mg_clktop2_hsclkctl);
+	val = I915_READ(MG_REFCLKIN_CTL(port));
+	val &= ~MG_REFCLKIN_CTL_OD_2_MUX_MASK;
+	val |= hw_state->mg_refclkin_ctl;
+	I915_WRITE(MG_REFCLKIN_CTL(port), val);
+
+	val = I915_READ(MG_CLKTOP2_CORECLKCTL1(port));
+	val &= ~MG_CLKTOP2_CORECLKCTL1_A_DIVRATIO_MASK;
+	val |= hw_state->mg_clktop2_coreclkctl1;
+	I915_WRITE(MG_CLKTOP2_CORECLKCTL1(port), val);
+
+	val = I915_READ(MG_CLKTOP2_HSCLKCTL(port));
+	val &= ~(MG_CLKTOP2_HSCLKCTL_TLINEDRV_CLKSEL_MASK |
+		 MG_CLKTOP2_HSCLKCTL_CORE_INPUTSEL_MASK |
+		 MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_MASK |
+		 MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_MASK);
+	val |= hw_state->mg_clktop2_hsclkctl;
+	I915_WRITE(MG_CLKTOP2_HSCLKCTL(port), val);
+
 	I915_WRITE(MG_PLL_DIV0(port), hw_state->mg_pll_div0);
 	I915_WRITE(MG_PLL_DIV1(port), hw_state->mg_pll_div1);
 	I915_WRITE(MG_PLL_LF(port), hw_state->mg_pll_lf);
