2 files changed, 34 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index c8fd8b94deaf..e137ba471e91 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1279,6 +1279,15 @@ enum skl_disp_power_wells {
 #define BXT_P_CR_GT_DISP_PWRON		_MMIO(0x138090)
 #define   GT_DISPLAY_POWER_ON(phy)	(1 << (phy))
 
+#define _BXT_PHY_CTL_DDI_A		0x64C00
+#define _BXT_PHY_CTL_DDI_B		0x64C10
+#define _BXT_PHY_CTL_DDI_C		0x64C20
+#define   BXT_PHY_CMNLANE_POWERDOWN_ACK	(1 << 10)
+#define   BXT_PHY_LANE_POWERDOWN_ACK	(1 << 9)
+#define   BXT_PHY_LANE_ENABLED		(1 << 8)
+#define BXT_PHY_CTL(port)		_MMIO_PORT(port, _BXT_PHY_CTL_DDI_A, \
+							 _BXT_PHY_CTL_DDI_B)
+
 #define _PHY_CTL_FAMILY_EDP		0x64C80
 #define _PHY_CTL_FAMILY_DDI		0x64C90
 #define   COMMON_RESET_DIS		(1 << 31)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index cb48b0d729e8..ad3b0ee5e55b 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1342,6 +1342,14 @@ bool intel_ddi_get_hw_state(struct intel_encoder *encoder,
 	DRM_DEBUG_KMS("No pipe for ddi port %c found\n", port_name(port));
 
 out:
+	if (ret && IS_BROXTON(dev_priv)) {
+		tmp = I915_READ(BXT_PHY_CTL(port));
+		if ((tmp & (BXT_PHY_LANE_POWERDOWN_ACK |
+			    BXT_PHY_LANE_ENABLED)) != BXT_PHY_LANE_ENABLED)
+			DRM_ERROR("Port %c enabled but PHY powered down? "
+				  "(PHY_CTL %08x)\n", port_name(port), tmp);
+	}
+
 	intel_display_power_put(dev_priv, power_domain);
 
 	return ret;
@@ -1745,6 +1753,8 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder)
 bool bxt_ddi_phy_is_enabled(struct drm_i915_private *dev_priv,
 			    enum dpio_phy phy)
 {
+	enum port port;
+
 	if (!(I915_READ(BXT_P_CR_GT_DISP_PWRON) & GT_DISPLAY_POWER_ON(phy)))
 		return false;
 
@@ -1770,6 +1780,21 @@ bool bxt_ddi_phy_is_enabled(struct drm_i915_private *dev_priv,
 		return false;
 	}
 
+	for_each_port_masked(port,
+			     phy == DPIO_PHY0 ? BIT(PORT_B) | BIT(PORT_C) :
+						BIT(PORT_A)) {
+		u32 tmp = I915_READ(BXT_PHY_CTL(port));
+
+		if (tmp & BXT_PHY_CMNLANE_POWERDOWN_ACK) {
+			DRM_DEBUG_DRIVER("DDI PHY %d powered, but common lane "
+					 "for port %c powered down "
+					 "(PHY_CTL %08x)\n",
+					 phy, port_name(port), tmp);
+
+			return false;
+		}
+	}
+
 	return true;
 }