diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index f3ba43c2ca22565492dde59f070f2c0fce303f2a..c839ce952a5045f776a50c9ddf3577f62edbdf30 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7811,9 +7811,11 @@ enum skl_disp_power_wells {
 #define  BXT_DSIC_16X_BY2		(1 << 10)
 #define  BXT_DSIC_16X_BY3		(2 << 10)
 #define  BXT_DSIC_16X_BY4		(3 << 10)
+#define  BXT_DSIC_16X_MASK		(3 << 10)
 #define  BXT_DSIA_16X_BY2		(1 << 8)
 #define  BXT_DSIA_16X_BY3		(2 << 8)
 #define  BXT_DSIA_16X_BY4		(3 << 8)
+#define  BXT_DSIA_16X_MASK		(3 << 8)
 #define  BXT_DSI_FREQ_SEL_SHIFT		8
 #define  BXT_DSI_FREQ_SEL_MASK		(0xF << BXT_DSI_FREQ_SEL_SHIFT)
 
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7c4ffcaf13c14579a81f432dddc6370501088b24..29aa64be1f03b385e13ca2f4d5a65d803d9f9eaf 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -36,6 +36,7 @@
 #include "intel_drv.h"
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
+#include "intel_dsi.h"
 #include "i915_trace.h"
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
@@ -9870,6 +9871,16 @@ static bool bxt_get_dsi_transcoder_state(struct intel_crtc *crtc,
 			continue;
 		*power_domain_mask |= BIT(power_domain);
 
+		/*
+		 * The PLL needs to be enabled with a valid divider
+		 * configuration, otherwise accessing DSI registers will hang
+		 * the machine. See BSpec North Display Engine
+		 * registers/MIPI[BXT]. We can break out here early, since we
+		 * need the same DSI PLL to be enabled for both DSI ports.
+		 */
+		if (!intel_dsi_pll_is_enabled(dev_priv))
+			break;
+
 		/* XXX: this works for video mode only */
 		tmp = I915_READ(BXT_MIPI_PORT_CTRL(port));
 		if (!(tmp & DPI_ENABLE))
diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index 96ea3f741a89e56354fe3a1014bade68849e543f..0de74e1b7ab393ce143b247c5f775d401f577c38 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -684,6 +684,14 @@ static bool intel_dsi_get_hw_state(struct intel_encoder *encoder,
 	if (!intel_display_power_get_if_enabled(dev_priv, power_domain))
 		return false;
 
+	/*
+	 * On Broxton the PLL needs to be enabled with a valid divider
+	 * configuration, otherwise accessing DSI registers will hang the
+	 * machine. See BSpec North Display Engine registers/MIPI[BXT].
+	 */
+	if (IS_BROXTON(dev_priv) && !intel_dsi_pll_is_enabled(dev_priv))
+		goto out_put_power;
+
 	/* XXX: this only works for one DSI output */
 	for_each_dsi_port(port, intel_dsi->ports) {
 		i915_reg_t ctrl_reg = IS_BROXTON(dev) ?
@@ -726,6 +734,7 @@ static bool intel_dsi_get_hw_state(struct intel_encoder *encoder,
 		break;
 	}
 
+out_put_power:
 	intel_display_power_put(dev_priv, power_domain);
 
 	return active;
diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
index e582ef8f3dac85d71ae19bd5bc2532a2c4bc0b1b..ec58ead9ccd1a956bb5c3614635954d9452f3c92 100644
--- a/drivers/gpu/drm/i915/intel_dsi.h
+++ b/drivers/gpu/drm/i915/intel_dsi.h
@@ -126,6 +126,7 @@ static inline struct intel_dsi *enc_to_intel_dsi(struct drm_encoder *encoder)
 	return container_of(encoder, struct intel_dsi, base.base);
 }
 
+bool intel_dsi_pll_is_enabled(struct drm_i915_private *dev_priv);
 extern void intel_enable_dsi_pll(struct intel_encoder *encoder);
 extern void intel_disable_dsi_pll(struct intel_encoder *encoder);
 extern u32 intel_dsi_get_pclk(struct intel_encoder *encoder, int pipe_bpp);
diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c
index e3e343c80221a2683a2475550756ee7ccf842a6e..4e53fcf6e0876b8617f922b130fa78fbef29088f 100644
--- a/drivers/gpu/drm/i915/intel_dsi_pll.c
+++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
@@ -192,6 +192,36 @@ static void vlv_disable_dsi_pll(struct intel_encoder *encoder)
 	mutex_unlock(&dev_priv->sb_lock);
 }
 
+static bool bxt_dsi_pll_is_enabled(struct drm_i915_private *dev_priv)
+{
+	bool enabled;
+	u32 val;
+	u32 mask;
+
+	mask = BXT_DSI_PLL_DO_ENABLE | BXT_DSI_PLL_LOCKED;
+	val = I915_READ(BXT_DSI_PLL_ENABLE);
+	enabled = (val & mask) == mask;
+
+	if (!enabled)
+		return false;
+
+	/*
+	 * Both dividers must be programmed with valid values even if only one
+	 * of the PLL is used, see BSpec/Broxton Clocks. Check this here for
+	 * paranoia, since BIOS is known to misconfigure PLLs in this way at
+	 * times, and since accessing DSI registers with invalid dividers
+	 * causes a system hang.
+	 */
+	val = I915_READ(BXT_DSI_PLL_CTL);
+	if (!(val & BXT_DSIA_16X_MASK) || !(val & BXT_DSIC_16X_MASK)) {
+		DRM_DEBUG_DRIVER("PLL is enabled with invalid divider settings (%08x)\n",
+				 val);
+		enabled = false;
+	}
+
+	return enabled;
+}
+
 static void bxt_disable_dsi_pll(struct intel_encoder *encoder)
 {
 	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
@@ -486,6 +516,16 @@ static void bxt_enable_dsi_pll(struct intel_encoder *encoder)
 	DRM_DEBUG_KMS("DSI PLL locked\n");
 }
 
+bool intel_dsi_pll_is_enabled(struct drm_i915_private *dev_priv)
+{
+	if (IS_BROXTON(dev_priv))
+		return bxt_dsi_pll_is_enabled(dev_priv);
+
+	MISSING_CASE(INTEL_DEVID(dev_priv));
+
+	return false;
+}
+
 void intel_enable_dsi_pll(struct intel_encoder *encoder)
 {
 	struct drm_device *dev = encoder->base.dev;