diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b9ed1b305beb..946b5df7b7df 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1924,6 +1924,7 @@ struct drm_i915_private {
 	 * crappiness (can't read out DPLL_MD for pipes B & C).
 	 */
 	u32 chv_dpll_md[I915_MAX_PIPES];
+	u32 bxt_phy_grc;
 
 	u32 suspend_count;
 	bool suspended_to_idle;
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index a3db4daec844..96234c589850 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1753,6 +1753,13 @@ static bool broxton_phy_is_enabled(struct drm_i915_private *dev_priv,
 	return true;
 }
 
+static u32 broxton_get_grc(struct drm_i915_private *dev_priv, enum dpio_phy phy)
+{
+	u32 val = I915_READ(BXT_PORT_REF_DW6(phy));
+
+	return (val & GRC_CODE_MASK) >> GRC_CODE_SHIFT;
+}
+
 static void broxton_phy_init(struct drm_i915_private *dev_priv,
 			     enum dpio_phy phy)
 {
@@ -1762,6 +1769,9 @@ static void broxton_phy_init(struct drm_i915_private *dev_priv,
 	if (broxton_phy_is_enabled(dev_priv, phy)) {
 		DRM_DEBUG_DRIVER("DDI PHY %d already enabled, "
 				 "won't reprogram it\n", phy);
+		/* Still read out the GRC value for state verification */
+		if (phy == DPIO_PHY1)
+			dev_priv->bxt_phy_grc = broxton_get_grc(dev_priv, phy);
 
 		return;
 	}
@@ -1857,8 +1867,8 @@ static void broxton_phy_init(struct drm_i915_private *dev_priv,
 			     10))
 			DRM_ERROR("timeout waiting for PHY1 GRC\n");
 
-		val = I915_READ(BXT_PORT_REF_DW6(DPIO_PHY1));
-		val = (val & GRC_CODE_MASK) >> GRC_CODE_SHIFT;
+		val = dev_priv->bxt_phy_grc = broxton_get_grc(dev_priv,
+							      DPIO_PHY1);
 		grc_code = val << GRC_CODE_FAST_SHIFT |
 			   val << GRC_CODE_SLOW_SHIFT |
 			   val;
@@ -1901,6 +1911,116 @@ void broxton_ddi_phy_uninit(struct drm_i915_private *dev_priv)
 	broxton_phy_uninit(dev_priv, DPIO_PHY0);
 }
 
+static bool __printf(6, 7)
+__phy_reg_verify_state(struct drm_i915_private *dev_priv, enum dpio_phy phy,
+		       i915_reg_t reg, u32 mask, u32 expected,
+		       const char *reg_fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+	u32 val;
+
+	val = I915_READ(reg);
+	if ((val & mask) == expected)
+		return true;
+
+	va_start(args, reg_fmt);
+	vaf.fmt = reg_fmt;
+	vaf.va = &args;
+
+	DRM_DEBUG_DRIVER("DDI PHY %d reg %pV [%08x] state mismatch: "
+			 "current %08x, expected %08x (mask %08x)\n",
+			 phy, &vaf, reg.reg, val, (val & ~mask) | expected,
+			 mask);
+
+	va_end(args);
+
+	return false;
+}
+
+static bool broxton_phy_verify_state(struct drm_i915_private *dev_priv,
+				     enum dpio_phy phy)
+{
+	enum port port;
+	u32 ports;
+	uint32_t mask;
+	bool ok;
+
+#define _CHK(reg, mask, exp, fmt, ...)					\
+	__phy_reg_verify_state(dev_priv, phy, reg, mask, exp, fmt,	\
+			       ## __VA_ARGS__)
+
+	/* We expect the PHY to be always enabled */
+	if (!broxton_phy_is_enabled(dev_priv, phy))
+		return false;
+
+	ok = true;
+
+	if (phy == DPIO_PHY0)
+		ports = BIT(PORT_B) | BIT(PORT_C);
+	else
+		ports = BIT(PORT_A);
+
+	for_each_port_masked(port, ports) {
+		int lane;
+
+		for (lane = 0; lane < 4; lane++)
+			ok &= _CHK(BXT_PORT_TX_DW14_LN(port, lane),
+				    LATENCY_OPTIM,
+				    lane != 1 ? LATENCY_OPTIM : 0,
+				    "BXT_PORT_TX_DW14_LN(%d, %d)", port, lane);
+	}
+
+	/* PLL Rcomp code offset */
+	ok &= _CHK(BXT_PORT_CL1CM_DW9(phy),
+		    IREF0RC_OFFSET_MASK, 0xe4 << IREF0RC_OFFSET_SHIFT,
+		    "BXT_PORT_CL1CM_DW9(%d)", phy);
+	ok &= _CHK(BXT_PORT_CL1CM_DW10(phy),
+		    IREF1RC_OFFSET_MASK, 0xe4 << IREF1RC_OFFSET_SHIFT,
+		    "BXT_PORT_CL1CM_DW10(%d)", phy);
+
+	/* Power gating */
+	mask = OCL1_POWER_DOWN_EN | DW28_OLDO_DYN_PWR_DOWN_EN | SUS_CLK_CONFIG;
+	ok &= _CHK(BXT_PORT_CL1CM_DW28(phy), mask, mask,
+		    "BXT_PORT_CL1CM_DW28(%d)", phy);
+
+	if (phy == DPIO_PHY0)
+		ok &= _CHK(BXT_PORT_CL2CM_DW6_BC,
+			   DW6_OLDO_DYN_PWR_DOWN_EN, DW6_OLDO_DYN_PWR_DOWN_EN,
+			   "BXT_PORT_CL2CM_DW6_BC");
+
+	/*
+	 * TODO: Verify BXT_PORT_CL1CM_DW30 bit OCL2_LDOFUSE_PWR_DIS,
+	 * at least on stepping A this bit is read-only and fixed at 0.
+	 */
+
+	if (phy == DPIO_PHY0) {
+		u32 grc_code = dev_priv->bxt_phy_grc;
+
+		grc_code = grc_code << GRC_CODE_FAST_SHIFT |
+			   grc_code << GRC_CODE_SLOW_SHIFT |
+			   grc_code;
+		mask = GRC_CODE_FAST_MASK | GRC_CODE_SLOW_MASK |
+		       GRC_CODE_NOM_MASK;
+		ok &= _CHK(BXT_PORT_REF_DW6(DPIO_PHY0), mask, grc_code,
+			    "BXT_PORT_REF_DW6(%d)", DPIO_PHY0);
+
+		mask = GRC_DIS | GRC_RDY_OVRD;
+		ok &= _CHK(BXT_PORT_REF_DW8(DPIO_PHY0), mask, mask,
+			    "BXT_PORT_REF_DW8(%d)", DPIO_PHY0);
+	}
+
+	return ok;
+#undef _CHK
+}
+
+void broxton_ddi_phy_verify_state(struct drm_i915_private *dev_priv)
+{
+	if (!broxton_phy_verify_state(dev_priv, DPIO_PHY0) ||
+	    !broxton_phy_verify_state(dev_priv, DPIO_PHY1))
+		i915_report_error(dev_priv, "DDI PHY state mismatch\n");
+}
+
 void intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp)
 {
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 089cf603a6f7..f587f7dd8ad9 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5468,6 +5468,11 @@ static bool broxton_cdclk_is_enabled(struct drm_i915_private *dev_priv)
 	return true;
 }
 
+bool broxton_cdclk_verify_state(struct drm_i915_private *dev_priv)
+{
+	return broxton_cdclk_is_enabled(dev_priv);
+}
+
 void broxton_init_cdclk(struct drm_i915_private *dev_priv)
 {
 	/* check if cd clock is enabled */
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index f8c26a5b715a..72153359cbb3 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1226,8 +1226,10 @@ void hsw_enable_pc8(struct drm_i915_private *dev_priv);
 void hsw_disable_pc8(struct drm_i915_private *dev_priv);
 void broxton_init_cdclk(struct drm_i915_private *dev_priv);
 void broxton_uninit_cdclk(struct drm_i915_private *dev_priv);
+bool broxton_cdclk_verify_state(struct drm_i915_private *dev_priv);
 void broxton_ddi_phy_init(struct drm_i915_private *dev_priv);
 void broxton_ddi_phy_uninit(struct drm_i915_private *dev_priv);
+void broxton_ddi_phy_verify_state(struct drm_i915_private *dev_priv);
 void bxt_enable_dc9(struct drm_i915_private *dev_priv);
 void bxt_disable_dc9(struct drm_i915_private *dev_priv);
 void skl_init_cdclk(struct drm_i915_private *dev_priv);
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index e3f70c53c57e..cb20606d7d57 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -799,6 +799,11 @@ static void gen9_dc_off_power_well_enable(struct drm_i915_private *dev_priv,
 					  struct i915_power_well *power_well)
 {
 	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
+
+	if (IS_BROXTON(dev_priv)) {
+		broxton_cdclk_verify_state(dev_priv);
+		broxton_ddi_phy_verify_state(dev_priv);
+	}
 }
 
 static void gen9_dc_off_power_well_disable(struct drm_i915_private *dev_priv,
@@ -2199,6 +2204,9 @@ void bxt_display_core_init(struct drm_i915_private *dev_priv,
 	broxton_init_cdclk(dev_priv);
 	broxton_ddi_phy_init(dev_priv);
 
+	broxton_cdclk_verify_state(dev_priv);
+	broxton_ddi_phy_verify_state(dev_priv);
+
 	if (resume && dev_priv->csr.dmc_payload)
 		intel_csr_load_program(dev_priv);
 }