diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 05125c7c2aa10e4f799a1ae93b92fc7f23125da0..c112bf758a668710013804a42c93a1102108ff54 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1316,6 +1316,7 @@ static void assert_pch_ports_disabled(struct drm_i915_private *dev_priv,
 			"PCH LVDS enabled on transcoder %c, should be disabled\n",
 			pipe_name(pipe));
 
+	/* PCH SDVOB multiplex with HDMIB */
 	assert_pch_hdmi_disabled(dev_priv, pipe, PORT_B, PCH_HDMIB);
 	assert_pch_hdmi_disabled(dev_priv, pipe, PORT_C, PCH_HDMIC);
 	assert_pch_hdmi_disabled(dev_priv, pipe, PORT_D, PCH_HDMID);
@@ -15655,6 +15656,65 @@ static void intel_early_display_was(struct drm_i915_private *dev_priv)
 	}
 }
 
+static void ibx_sanitize_pch_hdmi_port(struct drm_i915_private *dev_priv,
+				       enum port port, i915_reg_t hdmi_reg)
+{
+	u32 val = I915_READ(hdmi_reg);
+
+	if (val & SDVO_ENABLE ||
+	    (val & SDVO_PIPE_SEL_MASK) == SDVO_PIPE_SEL(PIPE_A))
+		return;
+
+	DRM_DEBUG_KMS("Sanitizing transcoder select for HDMI %c\n",
+		      port_name(port));
+
+	val &= ~SDVO_PIPE_SEL_MASK;
+	val |= SDVO_PIPE_SEL(PIPE_A);
+
+	I915_WRITE(hdmi_reg, val);
+}
+
+static void ibx_sanitize_pch_dp_port(struct drm_i915_private *dev_priv,
+				     enum port port, i915_reg_t dp_reg)
+{
+	u32 val = I915_READ(dp_reg);
+
+	if (val & DP_PORT_EN ||
+	    (val & DP_PIPE_SEL_MASK) == DP_PIPE_SEL(PIPE_A))
+		return;
+
+	DRM_DEBUG_KMS("Sanitizing transcoder select for DP %c\n",
+		      port_name(port));
+
+	val &= ~DP_PIPE_SEL_MASK;
+	val |= DP_PIPE_SEL(PIPE_A);
+
+	I915_WRITE(dp_reg, val);
+}
+
+static void ibx_sanitize_pch_ports(struct drm_i915_private *dev_priv)
+{
+	/*
+	 * The BIOS may select transcoder B on some of the PCH
+	 * ports even it doesn't enable the port. This would trip
+	 * assert_pch_dp_disabled() and assert_pch_hdmi_disabled().
+	 * Sanitize the transcoder select bits to prevent that. We
+	 * assume that the BIOS never actually enabled the port,
+	 * because if it did we'd actually have to toggle the port
+	 * on and back off to make the transcoder A select stick
+	 * (see. intel_dp_link_down(), intel_disable_hdmi(),
+	 * intel_disable_sdvo()).
+	 */
+	ibx_sanitize_pch_dp_port(dev_priv, PORT_B, PCH_DP_B);
+	ibx_sanitize_pch_dp_port(dev_priv, PORT_C, PCH_DP_C);
+	ibx_sanitize_pch_dp_port(dev_priv, PORT_D, PCH_DP_D);
+
+	/* PCH SDVOB multiplex with HDMIB */
+	ibx_sanitize_pch_hdmi_port(dev_priv, PORT_B, PCH_HDMIB);
+	ibx_sanitize_pch_hdmi_port(dev_priv, PORT_C, PCH_HDMIC);
+	ibx_sanitize_pch_hdmi_port(dev_priv, PORT_D, PCH_HDMID);
+}
+
 /* Scan out the current hw modeset state,
  * and sanitizes it to the current state
  */
@@ -15676,6 +15736,9 @@ intel_modeset_setup_hw_state(struct drm_device *dev,
 	/* HW state is read out, now we need to sanitize this mess. */
 	get_encoder_power_domains(dev_priv);
 
+	if (HAS_PCH_IBX(dev_priv))
+		ibx_sanitize_pch_ports(dev_priv);
+
 	/*
 	 * intel_sanitize_plane_mapping() may need to do vblank
 	 * waits, so we need vblank interrupts restored beforehand.